"Hell" if no Syrian deal - envoy

A plane flies overhead in Damascus…

.. and seconds later, smoke rises from this building.

The Internet video clip which Reuters cannot independently verify purports to show government air attacks continuing in urban areas.

Other video purportedly shows rebel fighters launching anti-aircraft fire at a government helicopter.

Rebels have appeared to be gaining ground in recent months - prompting renewed calls by Russian Foreign Minister Sergei Lavrov in Moscow today for a solution to the bloody 21-month conflict.

Lavrov - meeting with UN and Arab League envoy Lakhdar Brahimi after his recent trip to Damascus - said there was still a chance for a political settlement.

But he also firmly repeated Russia's stance that Syrian President Bashar al-Asad was not going anywhere.

Assad's exit should not be a precondition to talks, Lavrov said.

Brahimi, meanwhile warned of 'hell' if progress wasn't made.

"It is difficult, it is very complicated but there is no other choice if we want to be a responsible international community," he said.

Syrian oppositiion leaders on Friday however rejected a Russian invitation for talks and said they would 'not negotiate with the Assad regime."

Brahimi is to meet senior US and Russian diplomats together in the coming weeks to push for a breakthrough.