Among the warnings, Knight Ridder has learned, was a major study, called a National Intelligence Estimate, completed in October 2003 that concluded that the insurgency was fueled by local conditions -- not foreign terrorists -- and drew strength from deep grievances, including the presence of U.S. troops.

The existence of the top-secret document, which was the subject of a bitter three-month debate among U.S. intelligence agencies, has not been previously disclosed to a wide public audience.

The reports received a cool reception from Bush administration policy-makers at the White House and the office of Defense Secretary Donald Rumsfeld, according to the former officials, who discussed them publicly for the first time.

President Bush, Vice President Dick Cheney, Rumsfeld and others continued to describe the insurgency as a containable threat, posed mainly by former supporters of Saddam Hussein, criminals and non-Iraqi terrorists -- even as the U.S. intelligence community was warning otherwise.

Robert Hutchings, the chair of the National Intelligence Council from 2003 to 2005, said the October 2003 study was part of a ``steady stream'' of dozens of intelligence reports warning Bush and his top lieutenants that the insurgency was intensifying and expanding.

``Frankly, senior officials simply weren't ready to pay attention to analysis that didn't conform to their own optimistic scenarios,'' Hutchings said.

The NIC is the intelligence community's foremost group of senior analysts, and as its chair, Hutchings presided over the drafting of the October 2003 report and other analyses of the insurgency.

Tuesday in Congress, Army Lt. Gen. Michael Maples, the director of the Defense Intelligence Agency, testified that the insurgency ``remains strong and resilient.''

Maples said that while Iraqi terrorists and foreign fighters conduct some of the most spectacular attacks, disaffected Iraqi Sunnis make up the insurgency's core. ``So long as Sunni Arabs are denied access to resources and lack a meaningful presence in government, they will continue to resort to violence,'' he told the Senate Armed Services Committee.

A spokesman for the powerful Association of Muslim Scholars, meanwhile, blasted the government for failing to staunch the deadly sectarian attacks over the past week that have pushed the country toward civil war.

''It is clear that the government and its security forces are incapable of taking any action,'' said Abdul-Salam al-Kubaisi, a spokesman for the Sunni clerical group. Government forces, he said, should ''do their duty and withdraw to the Green Zone,'' the secure region in central Baghdad that houses the U.S. Embassy.

Al-Kubaisi denied Sunnis were behind the latest attacks, saying Shiite politicians and religious leaders were trying to inflame sectarian hatred ''to make use of these events and everything in this country to achieve one goal - to serve their future interests.''

Wednesday's most dramatic attack - a car bomb near a traffic police office in a primarily Shiite neighborhood in southeast Baghdad - killed at least 23 people and wounded 58, according to police Lt. Thaer Mahmoud.

About an hour earlier, a bomb hidden under a car detonated as a police patrol was passing near downtown Tahrir Square, said Interior Ministry Maj. Falah al-Mohammedawi. Police were unharmed but three civilians died and 15 were injured.

Also Wednesday, mortar shells fell on three houses in the mixed Sunni-Shiite town of Mahmoudiya, 20 miles south of Baghdad, killing three civilians, said police Capt. Rashid al-Samaraie.

The latest blasts occurred one day after Sunnis and Shiites in Baghdad traded bombings and mortar fire against mainly religious targets, killing at least 68 people following an end to curfews and vehicle restrictions that had briefly calmed a series of sectarian reprisal attacks.

At least six of Tuesday's attacks hit religious targets, concluding with a car bombing after sundown at the Shiite Abdel Hadi Chalabi mosque in the Hurriyah neighborhood that killed 23 and wounded 55. A separate suicide bombing killed 23 people at an east Baghdad gas station, where people had lined up to buy kerosine.

In addition to those known to have been killed Tuesday, police found nine more bullet-riddled bodies, including a Sunni Muslim tribal sheik, off a road southeast of Baghdad. It was unclear when they died.

Late Tuesday police reported finding the body of Shiite cleric Hani Hadi handcuffed, blindfolded and shot in the head near a Sunni mosque in Baghdad's notorious Dora neighborhood.

The surge of violence deepened the trauma of residents already shaken by fears the country was teetering on the brink of sectarian civil war, threatened talks among Iraqi politicians struggling to form a government and raised questions about U.S. plans to begin drawing down troop strength this summer.

Iraq began to tilt seriously toward outright civil war after the Feb. 22 bombing of the important Shiite Askariya shrine in the mainly Sunni city of Samarra, 60 miles north of Baghdad.

President Bush decried the latest surge in sectarian violence Tuesday and said that for Iraqis ''the choice is chaos or unity.''

''The people of Iraq and their leaders must make a choice,'' Bush said before leaving for a trip to South Asia. ''The choice is chaos or unity, the choice is a free society, or a society dictated by evil people who would kill innocents.''

Later, Bush said conversations with Iraqi leaders representing Shiite, Sunni and Kurdish factions helped reassure him that no larger role for the U.S. military is required and that the situation will not turn into all-out civil war.

The sectarian violence has hit Baghdad the hardest because the population in the capital is about evenly divided between Shiites and Sunnis, more so than in any other region of the country.

Before Wednesday's attacks, the government issued a statement declaring that 379 people had been killed and 458 wounded as of 4 p.m. Tuesday in the sectarian violence tied to the Askariya bombing.

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Associated Press Writer Alexandra Zavis contributed to this report from Baghdad

The sprawling Shiite slum of Sadr City is a stronghold of radical Shiite cleric Muqtada al-Sadr, who has reached across Iraq's sectarian divide and called for Sunni and Shiite solidarity in fighting U.S. occupation. It was not clear what caused the blast.

Mehdi Army militias loyal to Sadr patrol the streets of Sadr City, where violence that has hit other parts of the capital has been rare.

Earlier, a roadside bomb planted near a police station killed three people and wounded 10 in a market in southeastern Baghdad.

This comes after another bloody day on Wednesday, when two bomb attacks killed at least 26 people in Baghdad and mortar rounds fell on homes in a nearby town, killing four people.

And north of Baghdad, gunmen ambushed a police convoy, killing an unspecified number of officers and abducting another 10, police said. Four officers were seriously wounded.

The convoy of five minibuses was returning from a training session in Sulaimaniyah when it was attacked about 45 miles northeast of Tikrit, police Capt. Hakim al-Azzawi said. The assailants drove off in one of the minibuses.

U.S. troop cuts?
Despite the spike in violence, which has heightened worries about civil war there, the Pentagon continued discussing further cutting American forces, defense officials said on Wednesday.

Bryan Whitman, a senior Pentagon spokesman, said Army Gen. George Casey, the top U.S. commander in Iraq, planned to make a recommendation this spring to Defense Secretary Donald Rumsfeld and President Bush on future U.S. troop levels.

The United States has 133,000 troops in Iraq, the Pentagon said, down from about 160,000 in December when they were helping secure Iraq's parliamentary elections. The Pentagon has cut U.S. combat brigades to 15 from 17.

Defense officials previously have said the Pentagon was looking at options for troop levels in Iraq in 2006 including dropping down to about 100,000 if security and political conditions permit, but with other options for smaller cuts or none at all.

A defense official, speaking on condition of anonymity, said U.S. military commanders believed the U.S.-trained Iraqi security forces did "a tremendous job" containing a rash of sectarian violence triggered by last week's bombing of the Golden Mosque in Samarra.

That bolsters confidence that the Iraqi forces are capable of handling the load in the event the Pentagon cuts U.S. troop levels, the official said.

Baghdad's surge in attacks after a curfew was lifted Monday also prompted a spokesman for the powerful Association of Muslim Scholars to blast the Iraqi government for failing to staunch the violence between Shiite and Sunni Muslims.

"It is clear that the government and its security forces are incapable of taking any action," said Abdul-Salam al-Kubaisi, a spokesman for the Sunni clerical group. Government forces, he said, should "do their duty and withdraw to the Green Zone," the secure region in central Baghdad that houses the U.S. Embassy.

Al-Kubaisi denied Sunnis were behind the latest attacks, saying Shiite politicians and religious leaders were trying to inflame sectarian hatred "to make use of these events and everything in this country to achieve one goal - to serve their future interests."

Political maneuverings
Meantime on Wednesday, non-Shiite leaders mounted a challenge to Shiite-backed Prime Minister Ibrahim al-Jaafari, who has been nominated for a second term.

The call to withdraw that nomination is expected to draw sharp opposition from al-Sadr, whose support enabled al-Jaafari to win the nomination by a single vote in a Feb. 12 caucus of Shiites.

A political battle over al-Jaafari could further complicate efforts to form a national unity government - a key step in the U.S. plan to begin withdrawing its troops this year. Those efforts have been strained by a wave of sectarian violence triggered by the Feb. 22 bombing of a Shiite shrine.

Wednesday's most dramatic attack - a car bomb near a traffic police office in a primarily Shiite neighborhood in southeast Baghdad - killed at least 23 people and wounded 58, according to police Lt. Thaer Mahmoud.

About an hour earlier, a bomb hidden under a car detonated as a police patrol was passing near downtown Tahrir Square, said Interior Ministry Maj. Falah al-Mohammedawi. Police were unharmed but three civilians died and 15 were injured.

Also Wednesday, mortar shells fell on three houses in the mixed Sunni-Shiite town of Mahmoudiya, 20 miles south of Baghdad, killing three civilians, said police Capt. Rashid al-Samaraie. Another house was hit in Qadisiyah, another religiously mixed neighborhood in western Baghdad, killing a woman, police said.

The sprawling Shiite slum of Sadr City is a stronghold of radical Shiite cleric Muqtada al-Sadr, who has reached across Iraq's sectarian divide and called for Sunni and Shiite solidarity in fighting U.S. occupation. It was not clear what caused the blast.

Mehdi Army militias loyal to Sadr patrol the streets of Sadr City, where violence that has hit other parts of the capital has been rare.

Earlier, a roadside bomb planted near a police station killed three people and wounded 10 in a market in southeastern Baghdad.

This comes after another bloody day on Wednesday, when two bomb attacks killed at least 26 people in Baghdad and mortar rounds fell on homes in a nearby town, killing four people.

And north of Baghdad, gunmen ambushed a police convoy, killing an unspecified number of officers and abducting another 10, police said. Four officers were seriously wounded.

The convoy of five minibuses was returning from a training session in Sulaimaniyah when it was attacked about 45 miles northeast of Tikrit, police Capt. Hakim al-Azzawi said. The assailants drove off in one of the minibuses.

U.S. troop cuts?
Despite the spike in violence, which has heightened worries about civil war there, the Pentagon continued discussing further cutting American forces, defense officials said on Wednesday.

Bryan Whitman, a senior Pentagon spokesman, said Army Gen. George Casey, the top U.S. commander in Iraq, planned to make a recommendation this spring to Defense Secretary Donald Rumsfeld and President Bush on future U.S. troop levels.

The United States has 133,000 troops in Iraq, the Pentagon said, down from about 160,000 in December when they were helping secure Iraq's parliamentary elections. The Pentagon has cut U.S. combat brigades to 15 from 17.

Defense officials previously have said the Pentagon was looking at options for troop levels in Iraq in 2006 including dropping down to about 100,000 if security and political conditions permit, but with other options for smaller cuts or none at all.

A defense official, speaking on condition of anonymity, said U.S. military commanders believed the U.S.-trained Iraqi security forces did "a tremendous job" containing a rash of sectarian violence triggered by last week's bombing of the Golden Mosque in Samarra.

That bolsters confidence that the Iraqi forces are capable of handling the load in the event the Pentagon cuts U.S. troop levels, the official said.

Baghdad's surge in attacks after a curfew was lifted Monday also prompted a spokesman for the powerful Association of Muslim Scholars to blast the Iraqi government for failing to staunch the violence between Shiite and Sunni Muslims.

"It is clear that the government and its security forces are incapable of taking any action," said Abdul-Salam al-Kubaisi, a spokesman for the Sunni clerical group. Government forces, he said, should "do their duty and withdraw to the Green Zone," the secure region in central Baghdad that houses the U.S. Embassy.

Al-Kubaisi denied Sunnis were behind the latest attacks, saying Shiite politicians and religious leaders were trying to inflame sectarian hatred "to make use of these events and everything in this country to achieve one goal - to serve their future interests."

Political maneuverings
Meantime on Wednesday, non-Shiite leaders mounted a challenge to Shiite-backed Prime Minister Ibrahim al-Jaafari, who has been nominated for a second term.

The call to withdraw that nomination is expected to draw sharp opposition from al-Sadr, whose support enabled al-Jaafari to win the nomination by a single vote in a Feb. 12 caucus of Shiites.

A political battle over al-Jaafari could further complicate efforts to form a national unity government - a key step in the U.S. plan to begin withdrawing its troops this year. Those efforts have been strained by a wave of sectarian violence triggered by the Feb. 22 bombing of a Shiite shrine.

Wednesday's most dramatic attack - a car bomb near a traffic police office in a primarily Shiite neighborhood in southeast Baghdad - killed at least 23 people and wounded 58, according to police Lt. Thaer Mahmoud.

About an hour earlier, a bomb hidden under a car detonated as a police patrol was passing near downtown Tahrir Square, said Interior Ministry Maj. Falah al-Mohammedawi. Police were unharmed but three civilians died and 15 were injured.

Also Wednesday, mortar shells fell on three houses in the mixed Sunni-Shiite town of Mahmoudiya, 20 miles south of Baghdad, killing three civilians, said police Capt. Rashid al-Samaraie. Another house was hit in Qadisiyah, another religiously mixed neighborhood in western Baghdad, killing a woman, police said.