By Stephanie Nebehay
GENEVA (Reuters) - Aid agencies appealed to Libya's neighbors on Friday to keep borders open as they braced for an exodus of refugees from Libya following intensified fighting and the declaration of a no-fly zone.
Some 300,000 people, mainly migrant workers, have fled the North African country since the crisis began last month, mainly to Tunisia and Egypt, but increasingly to Algeria and Niger.
More Libyans have sought refuge in Egypt in the last few days, signaling the start of a possible massive outflow, and a convoy of 70 trucks carrying African migrants is reported to be heading for Libya's southern border with Niger, agencies said.
Muammar Gaddafi's government said it was declaring a unilateral ceasefire in its offensive to crush Libya's revolt, as Western warplanes prepared to attack his forces after the U.N. Security Council authorized military attacks to protect civilians.
"Events are changing on the ground more rapidly than we can appreciate. The imposition of the no-fly zone has implications which could impact on both the western and eastern borders," Andrew Harper of the U.N. refugee agency told a news briefing.
"If there is one strategy that we have, it is to be extremely flexible and prepare for the worst case scenario."
Official U.N. figures issued at the start of the crisis forecast up to 400,000 people fleeing Libya, split evenly between Tunisia and Egypt. But Harper said on Friday that this was the "public figure," declining to elaborate.
WORST CASE SCENARIO
"The worst case scenario would be if the governments of Egypt or Tunisia block the border. The borders have to be maintained, have to be kept open for the international community to be able to work," Harper said.
"While it has been largely a migratory flow so far, it could move very quickly into a (Libyan) refugee flow," he said.
Some 1,250 Libyans were among 2,300 fleeing to Egypt on Thursday, as fighting intensified in Ajdabiyah in the east and Libyan forces advanced on the rebel stronghold of Benghazi, according to the U.N. High Commissioner for Refugees (UNHCR).
"We are not seeing a mass exodus at this point. But we're not convinced the numbers necessarily reflect the reality," UNHCR spokeswoman Sybella Wilkes told Reuters. More people lacking identity papers were arriving and not being counted.
Fernando Calado of the International Organization for Migration (IOM), said: "We understand that there is an important convoy of (sub-Saharan African) migrants on their way, trying to get to the border with Niger from Libya. So basically the message we are trying to convey today is we need to remain flexible as the unpredictable situation evolves."
Some 50,000 third country nationals, of the 300,000 people who fled Libya to Tunisia or Egypt so far, have already been flown home by the UNHCR and IOM. They include many Bangladeshis, Ghanaians and Sudanese.
"This is one of the biggest humanitarian evacuations in history," IOM director-general William Lacy Swing said in a statement on Friday appealing for further international funding.
The aim is to relieve pressure on border areas, so new arrivals can be accommodated, UNHCR spokeswoman Wilkes said.
UNHCR and IOM, which have spent a total of $43 million on the Libyan crisis to date, need up to a further $82 million for the coming month, she added.
"This humanitarian crisis is far from over," said Antonio Guterres, U.N. High Commissioner for Refugees.
(Editing by Philippa Fletcher)