Libyans fleeing the advance of Muammar Gaddafi's forces on the rebel stronghold of Benghazi are crossing into Egypt in growing numbers, the United Nations refugee agency said on Tuesday.

Spokeswoman Sybella Wilkes said the UNHCR was prepared to provide supplies and temporary shelter for a sudden influx after Gaddafi's troops forced insurgents out of the last major town before Benghazi in eastern Libya.

"Until this week, it was almost entirely migrant workers crossing into Egypt. But on Monday nearly half of the around 2,250 people were Libyans, including many families with children," she told Reuters.

"On the Egyptian side of Libya, we haven't seen that before."

A Reuters correspondent said the poorly armed rebels pulled out of Ajdabiyah after the town was attacked by land and air, and Libyan state television said Gaddafi forces were now in full control there.

Soliman Bouchuiguir, the president of a Libyan exile human rights organisation in Geneva and who for many years worked for the U.N., told Reuters on Monday he expected "a bloodbath, a massacre like we saw in Rwanda" if Benghazi fell.

Also on Monday, the office of the U.N. High Commissioner for Human Rights Navi Pillay said Gaddafi was using indiscriminate force against his own people and that the international community was obliged to intervene.

But efforts by France and Britain to get agreement on a no-fly zone grounding Gaddafi's air force have failed both at the United Nations in New York and in Paris on Tuesday at a meeting of the G8 foreign ministers.

The UNHCR's Wilkes said it was feared that Gaddafi's forces might close the main road allowing people to flee from Benghazi -- a city of a million people with a tradition of opposition to the long-time Libyan leader -- through Tobruk to Egypt.

"We are appealing to all parties to ensure safe passage for all civilians fleeing violence," chief UNHCR spokeswoman Melissa Fleming told a news briefing in Geneva earlier.

Speaking before the fall of Ajdabiyah, which controls a crossroads which could allow Gaddafi troops to encircle Benghazi by heading northeast along the road to Tobruk, Fleming set out what might happen in the next hours and days.

"Typically, we would expect to see significant numbers of injured people and women and children in a mass displacement," she said.

Separately, the Swiss-based International Committee of the Red Cross said a ship it had chartered docked at Benghazi on Tuesday with a cargo of 180 tonnes of food and other essential items like blankets and soap for people in the city.

"Our current priority in Benghazi is to ensure that there is adequate capacity to respond to emergency situations," ICRC quoted its mission chief in the city, Simon Brooks, as saying.

The independent ICRC is one of the only international aid agencies deployed in Libya during the crisis, but has been confined to the east due to the insecurity.

After widespread protests against Gaddafi's rule put much of the country in rebel hands last month, well over 200,000 refugees -- few of them Libyans -- crossed westwards into Tunisia where camps were set up to receive them.

Wilkes said there were no camps yet on the Egyptian side, but those Libyans who had crossed up to now had quickly left the frontier area.