Iran closed the state-run Farsi language newspaper Iran and detained its chief editor and cartoonist on Tuesday for publishing a cartoon that showed a cockroach speaking Azeri and suggested that ethnic Azeris are stupid.

It was the first closure of a newspaper since Ahmadinejad came to office last year - and the heavy response, along with public apologies by Iranian officials, suggested the government is concerned the United States may try to stir up trouble among Iran's ethnic minorities.

"Today, they (the U.S. and its allies) are hatching plots. They want to provoke differences, divisions, disappointment ... to prevent the Iranian nation from achieving all of its rights," Ahmadinejad told thousands of people in Khorramshahr in southwestern Iran.

Other Iranian officials were also quick to stress the nation's unity in the standoff with Washington, which accuses Iran of seeking to develop nuclear weapons.

"It is clear that the evil hands of foreigners are making efforts to provoke tribal, ethnic, and religious differences under the present circumstances," State Public Prosecutor Ghorban Ali Dorri Najafabadi was quoted Tuesday as saying by state-run media.

Hundreds of Azeris marched on Monday in the northwestern city of Tabriz to protest the cartoon. Some broke windows at the governor's office, and police had to use tear gas to disperse the crowd, witnesses said. The violence was also reported by an independent news agency, ILNA.

Azeris, a Turkic ethnic group, are Iran's largest minority, making up about a quarter of Iran's 70 million people, dominated by ethnic Persians. Azeris speak a Turkic language shared by their brethren in neighboring Azerbaijan.

The cartoon, which ran May 12, showed people from different walks of life - including an athlete and a tradesman - trying to teach the cockroach and he always answers, in Azeri, "What do you mean?" There was no explanation why the protests broke out more than a week after the cartoon.

State television said the daily, one of the country's top three newspapers, had been closed "due to its publication of divisive and provocative materials." Tehran prosecutor Saeed Mortazavi said the paper's cartoonist and editor-in-chief had been taken to Evin prison.

Iran saw a wave of newspaper closures in past years amid the confrontation between reformers and hard-liners during the 1997-2005 presidency of reformist
Mohammad Khatami. The hard-line judiciary shut more than 100 pro-reform newspapers and jailed dozens of editors and writers.

But the government of Ahmadinejad, an ultra-conservative, has taken no steps against the remaining two moderate newspapers that still publish - though they make few of the sharp criticisms of the cleric-led leadership that reformers did.

Instead, Tuesday's closure aimed to ensure national unity at a time when Iran takes seriously the possibility of U.S. military action over the nuclear issue.

A January article in The New Yorker magazine reported that U.S. military operatives were already working in Iran, making contacts with anti-government ethnic minorities and gathering intelligence. Defense Department officials said the article was filled with mistakes but did not deny its basic point. Iran denied that any U.S. agents had entered its territory.

Iran is a patchwork of many ethnic groups, but its numerous minorities have generally been quiet in past decades with little overt show of opposition to the government.

But there have been worrisome signs.

A series of bomb attacks have occurred in the past year in Khuzestan, the center of Iran's Arab minority, where Ahmadinejad spoke Wednesday. An Iranian Arab insurgent group claimed responsibility for a Jan. 24 blast that killed six people and wounded 46. The Iranian government blamed the bombings on Britain and United States, which denied any involvement.

In April, Iranian troops fired artillery and rockets at Iranian Kurdish guerrillas in
Iraq amid reports they were crossing the border to infiltrate Iran's Kurdish minority.

On Tuesday, Interior Minister Mostaf Pourmohammadi warned that opportunists were working in Iran to inflame trouble.

"Some are misusing the situation. Others outside (Iran's) borders are trying to propagate protests through their satellite channels," he said in reference to U.S.-based Iranian opposition television channels.

"We should preserve our vigilance, especially the media ... and not allow, under the current very important situation the country is in now, others who pursue certain intentions to misuse the situation," he said.

France, Britain and Germany discussed the final form of the package Tuesday ahead of submission for hoped-for approval Wednesday at a formal meeting of the five permanent Security Council members and Germany.

If accepted, the compromise would resolve wrangling within the Security Council since it became actively involved in March, two months after Iran's file was referred to it by the 35-nation board of the
International Atomic Energy Agency.

Russia and China have opposed calls by America, Britain and France for a resolution threatening sanctions and enforceable by military action.

The compromise proposal is meant to break that deadlock, said the diplomats, who demanded anonymity in exchange for discussing the package with The Associated Press.

If Iran remains defiant, the proposal calls for a Security Council resolution imposing sanctions under Chapter VII, Article 41 of the U.N. Charter. But it avoids any reference to Article 42 - which is the trigger for possible military action to enforce any such resolution.

And in an additional reassurance to Moscow and Beijing, it specifically calls for new consultations among the five permanent Security Council members on any further steps against Iran. That is meant to dispel past complaints by the Russians and Chinese that once the screws on Iran are tightened, it would automatically start a process leading to military involvement.

The proposed language represents compromise by the United States, Britain and France, which for weeks had called for a full Chapter VII resolution automatically carrying the threat of military action if ignored by Iran.

Still, it was unclear whether the changes would be enough to satisfy Russia and China at the six-nation meeting Wednesday because any such resolution would still declare Iran a threat to international peace - something also opposed by both Moscow and Beijing. Russia and China also have until recently spoken out against possible sanctions on Tehran, their economic and strategic partner.

On the eve of the meeting, Russian news agencies cited Foreign Minister Sergey Lavrov as again calling for political and diplomatic means to solve the Iranian nuclear impasse.

Still, Lavrov also said Moscow favors the approach of the three
European Union countries in handling the crisis - a possible suggestion that it was ready to accept the modified proposal for a council resolution as part of the package of carrots if Iran cooperated - and sticks if it didn't.

The draft European proposal, shared in part with The Associated Press, listed among possible sanctions to imposed by the council banning travel visas for government officials; freezing assets; banning financial transactions of key government figures and those involved in Iran's nuclear program; an arms embargo, and an embargo on shipping refined oil products to Iran. While Iran is a major exporter of crude it has a shortage of gasoline and other oil derivatives.

If Tehran agrees to suspend enrichment, enter new negotiations on its nuclear program and lift a ban on intrusive inspections by the IAEA, they would be offered rewards including agreement by the international community to "suspend discussion of Iran's file at the Security Council."

The package also promised help in "the building of new light-water reactors in Iran," offered an assured supply of nuclear fuel for up to five years, and asked Tehran to accept a plan that would move its enrichment program to Russia.

A European official said Washington was unlikely to compromise beyond giving up insistence that any council resolution be automatically militarily enforceable.

Concern has been building since 2002 when Iran was found to be working on large-scale plans to enrich uranium. Iran insists it is only interested in generating electricity, but the international community increasingly fears it plans to build a nuclear bomb.

A series of IAEA reports since then have revealed worrying secret activities and documents, including drawings of how to mold weapons-grade uranium metal into the shape of a warhead.

Iran heightened international worries by announcing on April 11 that it had enriched uranium with 164 centrifuges. Experts estimate that Iran could produce enough nuclear material for one bomb if it had at least 1,000 centrifuges working for more than a year.

Sheikh Mohammad said it was very important for Iran's nuclear issue to be resolved in a peaceful, political and diplomatic manner.

The visiting Russian foreign minister said "we both thought that Iran's nuclear issue should be solved through peaceful means and we supported the desire of Kuwait and most countries in the region to solve the crisis through peaceful and diplomatic means."

Lavrov said that Russia did not believe that the use of force in international relations was a means of resolving crises.

"What is important ... is that Iran takes a positive stance and we hope Tehran accepts the negotiated initiatives and that it accepts total cooperation with the International Atomic Energy Agency," Lavrov said.

Ahmadinejad thanked Chavez for endorsing Iran's right to developing nuclear energy for peaceful purposes, and said the two countries shared many "ideals and goals" which "have formed strong bonds between our two nations."

He said that independent-minded governments could, with harmony, unity and wisdom, preserve and strengthen their natural resources.

"As part of the vindication of our inalienable right to develop nuclear energy for peaceful means, we will continue to act in the framework of legality and with civilized logic," he said.

Chavez reiterated his support for Iran's civil use of nuclear power, saying he was sure that Iran would proceed with its nuclear program with wisdom and that Iran's people would succeed in the field.

He also called for the advancement of the joint projects Iran and Venezuela were planning.

The U.S. government accuses Iran of trying to develop nuclear weapons, an accusation which Iran denies, insisting that it wants nuclear energy for peaceful purposes.

But General Talaie said Tuesday night's unrest was "provoked by 20 or 30 supposed students joined by thugs from outside the university". He said police responded with "tolerance and restraint" and arrested no students.

"These people had their faces covered, but some of them have been identified," the general said.

Tehran University was the scene of violent clashes in 1999, when students protested over the closure of a pro-reform newspaper and the subsequent intervention by Islamist militiamen from the Basij force.

Another university in Tehran was also reported to have seen protests late on Tuesday.

Students at the Amir Kabir University, one of the country's most prestigious technical colleges, demostrated against "the intervention of Basij in elections" for members of the Islamic Student Association -- one of the few remaining pro-reform groups still operating on campus.

The student news agency ISNA said protestors shouted slogans including "we don't want the Islam of the Taliban" and "death to reactionaries and dictatorship."