GENEVA (Reuters) - Up to 700,000 Syrian refugees may flee abroad by the end of the year, the U.N. refugee agency said on Thursday, nearly quadrupling its previous forecast for the exodus from the deepening crisis.
Most faced what was likely to be a bitterly cold winter living in tents with little prospect of returning to their homeland, it said. The agency urged Western donors to help raise nearly $500 million to finance aid operations in four neighbouring countries that have kept their borders open so far.
About 294,000 refugees fleeing 18 months of conflict in Syria have already crossed into Jordan, Iraq, Lebanon and Turkey, or await registration there, the UNHCR said.
"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 the U.N. High Commissioner for Refugees (UNHCR), told a news briefing.
"The most important part is the preparing for winter months.
The winter period is very harsh in that region," he said.
The UNHCR's previous forecast - of 185,000 refugees - was surpassed in August. It had been made in June.
The uprising against President Bashar al-Assad, which erupted in March last year, has become an armed insurgency in which activists say 30,000 people have been killed. A further 1.2 million have been uprooted within Syria, the United Nations says.
Bombardment and heavier fighting between government forces and militants is forcing Syrians to flee hot spots across the country, Moumtzis said. Many cross borders with only the clothes on their backs after a perilous journey through frontlines.
"These are families, women and children who escaped Homs, Hama, Deraa, Idlib, Aleppo who have come out with traumatic experiences and have told us they have fled," Moumtzis said.
The surge has overwhelmed aid workers as 15,000 to 20,000 refugees now arrive each week, needing basic services including shelter, latrines, food, clean water and health care.
"For example, Zaatri camp, which is a town, did not exist until 30 days ago, it was a piece of desert basically," he said, referring to Jordan's sprawling camp of some 31,000 refugees.
Other Syrians, who fled the uprising early on, now find they have depleted their savings a nd are registering as refugees.
In all, 500,000 Syrians are estimated to have already fled to the four countries, according to the UNHCR, but only some 300,000 have signed up for protection and assistance so far.
Some 52 aid agencies on Thursday issued a U.N. funding appeal for $487.9 million to help meet growing needs before a bitter winter sets in.
They are struggling to provide winterised tents, caravans, blankets, clothing, and food for up to 700,000 refugees expected to be staying in camps or as guests in host communities.
"It is generally assumed that Syrian refugees will remain in the neighbouring countries until the situation inside Syria stabilises, allowing them to return in safety," the appeal said.
Turkey, which currently hosts 87,774 refugees in 13 camps is building three more, while most of the 94,716 refugees in Jordan are staying with host families, apart from those at Zaatri where hundreds rioted this week.
Lebanon does not have any camps but is hosting 78,452. Most of the 33,063 in Iraq are in a single camp in the north.
"We are running against time with winter coming," said Edward Kallon of the World Food Programme, the U.N. agency which aims to provide hot meals or other rations to nearly 200,000 Syrian refugees this month and roughly double that by year-end.
Women and children make up about 75 percent of the refugee population, and education and health care are priorities.
"Over half of the refugee population are under 18 and a fifth are under five and these are always the most vulnerable," said Dermot Carty, Deputy Director of Emergency Programmes at the U.N. Children's Fund (UNICEF).
"Schooling continues to be a problem," he said.
About 5,000-6,000 Syrians have reached other parts of north Africa, mainly Egypt, while 15,000 refugees have turned up in Europe, including in Cyprus and Greece, according to the UNHCR. Others have arrived in Armenia and Georgia.
It forecast that Jordan could host 250,000 by the end of the year, Lebanon 120,000, Turkey 280,000 and Iraq 60,000.
Moumtzis paid tribute to Syria's neighbours for keeping their borders open but said donors needed to share the financial burden of caring for the refugees.
"The most important thing for all of us is to make sure they are in a safe place," he said.
Reporting by Stephanie Nebehay; Editing by Andrew Osborn