Syrian rebel fighter

REUTERS

Syrian rebels said they had launched a major attack in Aleppo on Thursday at the start of a "decisive battle" to push President Bashar al-Assad's forces out of the country's biggest city.

Heavy fighting was reported in around 14 districts by opposition activists and several rebel brigades, though the scale of the fighting could not be confirmed independently, reports Reuters.

A video posted on YouTube by rebels showed Abdulqadir al-Saleh, the head of the biggest rebel force in Aleppo, the Tawheed Brigade, carrying a walkie talkie and announcing the start of the assault.

"Now the attack on Assad's forces has started on all fronts and God willing today will be decisive in Aleppo," he said.

The 18-month-old uprising against Assad has killed 30,000 people and the violence is escalating sharply, say activists. World powers are meeting at the United Nations but are divided over the crisis, which has descended into civil war.

The U.N. refugee agency said up to 700,000 Syrian refugees may flee the country by the end of the year, nearly quadrupling its June forecast for the exodus from the deepening crisis.

Around 294,000 refugees have crossed into neighboring Jordan, Iraq, Lebanon and Turkey, most of them in the last two months.

"This is a significant outflow taking place, 100,000 people in August, 60,000 in September and at the moment 2,000 or 3,000 per day or night," Panos Moumtzis, Regional Refugee Coordinator for UNHCR, said on Thursday in Geneva.

The flow of refugees surged in August when Assad deployed jets and helicopters to strike rebel-held towns in the northern provinces of Aleppo and Idlib, sending thousands across the border with Turkey.