Syrian government troops and rebels clashed again in Aleppo on Monday.
The regime claims to have wrestled back control of the Salaheddine district from anti-government fighters.
That has been denied by the Free Syrian Army.
Amateur video posted online showed that fighting is still raging in the stragetically-important area.
One rebel fighter claimed that his men had seized a checkpoint in nearby Anadan and captured a number of military vehicles from President Bashar Assad’s forces.
The UN says as many as 200,000 people have fled the city in the past two days to escape the violence.
The opposition Syrian National Council is urging the Security Council to call an emergency session on the situation in Aleppo.
The 15-member body has voted three times in an attempt to stop the fighting in Syria, but Russia and China have vetoed the proposals on each occasion.