(AP Photo/Peter Dejong)

VIENNA - Russia's foreign minister on Wednesday blamed "external actors" for prolonging Syria's agony, suggesting that the U.S. and its allies opposed negotiations to end the bloodshed there and were responsible for torpedoing a U.N. resolution aimed at calming the situation.

Sergey Lavrov also seized on a call by the al-Qaida terror network to topple Syrian President Bashar Assad to caution that little was known about those opposing the regime in Damascus, and implied that the opposition could not be trusted to run the country if victorious.

He also welcomed Assad's announcement that he had ordered a Feb. 26 referendum on a new constitution that would open the way to political parties in Syria other than the ruling Baath Party.

Russia and China vetoed a Security Council resolution earlier this month brought by the Arab League that aimed to halt Syria's violence - angering many Western powers and Arab states. The U.N. estimates well over 5,400 people have died in the Syrian regime's crackdown on protesters in the past year.

Lavrov and other foreign ministers were in Vienna for a conference Thursday to discuss ways to reduce the drug flow from Afghanistan. But Syria was the dominant issue during his talks Wednesday with Austrian Foreign Minister Michael Spindelegger and was likely to dominate talks on the sidelines Thursday.

Lavrov told reporters that he would meet with French Foreign Minister Alain Juppe on Thursday to be briefed on a French plan that envisages setting up violence-free "human corridors" in Syria. But he insisted any plan to reduce the carnage must be approved by all sides in the conflict.

The Russian foreign minister defended Moscow's stance against the U.N. Security Council resolution, saying "it wasn't us who slammed the door" on council agreement Feb. 5. Refusal by Western permanent Security Council members to accept Russian insistence that not only Syrian army units but rebels also withdraw from urban battle zones essentially was "a demand on the regime to capitulate," he said.

He blamed "some external actors" - shorthand for Washington and its Western allies - for allegedly persuading the rebels not to negotiate, a tactic that he said "can only lead to (further) massive losses of human life."

Al-Qaida chief Ayman al-Zawahri has called on Muslims to support the Syrian rebels, raising fears that Islamist extremists will try to exploit the uprising, and Lavrov emphasized such concerns Wednesday.

"Who are these people? Nobody knows," he said alluding to the anti-Assad forces. "The Muslim Brotherhood ... there are deserters, al-Qaida is represented."

Lavrov came from the Netherlands, where, after meeting with Dutch Foreign Minister Uri Rosenthal, he said Russia would not support any U.N. resolution "that could legitimize regime change."

Earlier in the day, White House spokesman Jay Carney called Assad's plans for a referendum on a new constitution "quite laughable." But Lavrov praised the move.

"A new constitution to end one-party rule in Syria is a step forward," Lavrov said. "It is coming late, unfortunately, but better late than never."

Carney, however, said any attempt to hold a constitutional referendum now "makes a mockery" of the Syrian uprising.