The Syrian army has begun bombarding Aleppo, amid fears of an imminent bloodbath in the country’s second largest city.
The foreign-based Syrian Observatory for Human Rights says helicopter gunships have been used to attack several western districts.
The government is believed to be planning a decisive battle against rebels. Thousands of civilians are said to have left.
Tanks have been gathering around the northern city. A pro-government newspaper has spoken of the “mother of all battles” about to begin.
Thursday’s fighting is thought to have killed dozens of people. Rebels have been launching small-scale attacks on security forces and are said to control several parts of Aleppo.
The UN High Commissioner for Human Rights has said she is deeply alarmed at the prospect of an imminent major confrontation and the threat to civilians. The US said it feared Syria’s army was about to carry out a massacre.
The International Committee of the Red Cross (ICRC) is evacuating some expatriate aid workers from Syria due to the deteriorating security situation, moving them temporarily to Beirut, a spokesman said on Friday.
State TV has broadcast pictures of government forces fighting rebels in Damascus.
Soldiers said they were seeking to restore calm and security, and liberate the country from what they called “terrorists and armed gangs”.
In the days following last week’s bomb attack on President Assad’s inner team, government forces have toughened their response to the armed revolt.
They are expected to use the same tactics in Aleppo.