London: The UN's refugee agency has warned that around 700,000 people could flee Syria by the end of the year, BBC reported Thursday.
Around 294,000 refugees have already left Syria, and the UNHCR is appealing for $490 million to deal with the crisis.
Most of the refugees are housed in camps in Turkey, Lebanon and Jordan.
A Britain-based activist group said that Wednesday was the bloodiest day in the 18-month-old conflict so far, with at least 305 people being killed.
Rami Abdel Rahman from the Syrian Observatory for Human Rights said the figure included only those whose names had been documented.
"If we count the unidentified bodies, the figure will be much higher," he was quoted as saying by the BBC.
The group said 199 of the dead were civilians.
The UNHCR said between 2,000 and 3,000 refugees were fleeing the violence every day and entering into neighbouring countries.
"Many refugees are arriving with only the clothes on their backs," said Panos Moumtzis, the UN agency's regional co-ordinator for Syrian refugees.