Hezbollah leader Hassan Nasrallah said on Sunday the rebels in Syria cannot emerge victorious from the 21-month-long conflict.

Nasrallah, a staunch ally of President Bashar Assad, said: "The situation in Syria is getting more complicated - but anyone who thinks the armed opposition can settle the situation on the ground is very, very mistaken."

Syrian rebels accuse the Shi'ite group of sending fighters to Syria to help Assad, who is trying to crush a revolt against his rule. The group denies these accusations.

Over the weekend, Russia's Foreign Ministry denied that a top diplomat said Assad is losing control of his country, a statement that had been interpreted as signaling a shift in Russia's assessment of the situation.

Deputy Foreign Minister Mikhail Bogdanov, the ministry's point man on Syria, was quoted by two state-owned Russian news agencies on Thursday as saying that "there is a trend for the government to progressively lose control over an increasing part of the territory," adding that "an opposition victory can't be excluded."

But the Russian Foreign Ministry on Friday insisted in a statement that Bogdanov "has not made any statements or special interviews recently" on Syria but was simply citing the stance of the Syrian opposition while giving a speech.

Meanwhile, Syrian fighter jets fired at least two rockets at the Palestinian Yarmouk camp in Damascus on Sunday, for the first time since the revolt against Bashar Assad erupted last year, activists in the capital said.

They said dozens of people were killed when at least one rocket hit a mosque in the camp sheltering refugees who fled the violence in nearby suburbs of Damascus.