© Reutersal-CIA-duh: Damaged cars are seen outside a military security building, one of two sites of bomb blasts in Syria's northern city of Aleppo February 10, 2012
Al-Qaeda's branch in Iraq likely carried out recent suicide bombings in Syria and has infiltrated opposition forces fighting President Bashar al-Assad's regime, the US spy chief said last night.

Bombing attacks in Damascus and Aleppo since December "had all the earmarks of an al-Qaeda-like attack," James Clapper, Director of National Intelligence, told the Senate Armed Services Committee.

"And so we believe al-Qaeda in Iraq is extending its reach into Syria," he said.

His comments confirmed earlier reports that US officials suspected al-Qaeda's hand in the bombings and follows a recent video message from al-Qaeda leader Ayman al-Zawahiri in which he endorses the uprising against Assad's rule.

Iraq's deputy interior minister told AFP this month that al-Qaeda was moving guns and militants from Iraq into Syria.

Mr Clapper voiced concern that Al-Qaeda militants had inserted themselves inside a divided opposition amid the spiraling violence that activists say has left more than 6,000 people dead since March 2011.

Comment: No, al Qaeda have been inserted by their handlers.

"Another disturbing phenomenon that we've seen recently, apparently, is the presence of extremists who have infiltrated the opposition groups.

"The opposition groups in many cases may not be aware that they're there," he said.

Defence Secretary Leon Panetta, speaking at a news conference with his German counterpart, Thomas De Maiziere, echoed Mr Clapper's view but said al-Qaeda's influence on the opposition remained unclear.

Asked if Washington could support opposition forces given al-Qaeda's presence, Panetta said: "I think just the fact that they're present concerns us. As to what their role is, and how extensive their role is, I think that remains to be seen."

Mr Clapper said the opposition was deeply fragmented and that the Assad regime appeared able to hold on to power for the moment as it pressed ahead with the violent repression of protests.

He added there was no sign the stalemate would end anytime soon.

Mr Clapper also said US intelligence agencies were monitoring Syria's "extensive network" of chemical weapon stockpiles, which he said presented a bigger challenge than Libya's arsenal did before the fall of dictator Muammar Gaddafi.

"Although to this point, and we're watching these very carefully, they appear to be secure," he said.