Fierce fighting has been reported in Syria's second city of Aleppo, a day after the rebel Free Syrian Army (FSA) said a "decisive" battle had begun.
Both residents and activists described the clashes as "unprecedented", and said rebel fighters were attacking government positions on several fronts.
The fighting had spread to previously peaceful districts, they added.
On Thursday, the UN said the number of Syrians fleeing to other states could exceed 700,000 by the end of the year.
More than half a million are believed to have already crossed into Turkey, Jordan, Lebanon and Iraq, but only 294,000 have registered with the UN.
UN agencies and other humanitarian groups have issued a funding appeal for $488m (£300m) to help them meet the needs of the refugees...