BBC news with Nick Kelly.

Several districts of Syria's biggest city Allepo have come under heavy bombardment. An armed rebel says the government offensive to

flush them out

. Ian Pannell has been in Allepo throughout the day.

I saw residents from burst light trying to get out, trucks loaded with families of three generations, grandparents, children, all

crammed

into vehicles and trying to head out into the countryside. From again first light, there was a sound of intensive artillery bombardment from far away from where we were staying. And that continued in different areas throughout the day, we saw helicopters overhead, we heard jet too. But it would probably be

skirmishing

and fighting which stuck out the most. There were already clashes between government forces and the armed opposition in many neighbourhood.

The Russian foreign minister Sergei Lavrov said that tragety was unfolding in Allepo but it was unrealistic to expect the Syrian government to to accept the presence of an armed opposition.

“While armed opposition groups are occupying cities, trying to creat

buffer zones

so they can set up a transitional government, how can you expect Syrian government to say yes, go ahead, overthrow me. This is simply unrealistic. Not because we are backing the regime but because it just wouldn’t work.”

The French President Froncios Hallonde urged the members of the United Nations Security Council to interven in Syria as soon as possible.