Lebanon should consider setting up transit centres to absorb the waves of refugees fleeing neighbouring Syria and may have to establish formal refugee camps if the influx continues, a United Nations refugee official said.

The tiny and fragile Mediterranean state already hosts 260,000 refugees - equivalent to 6.5 per cent of its population - and has sought to absorb them in homes and communities, fearing large camps of Sunni Muslim Syrians could inflame sectarian tensions still smouldering from its own 1975-1990 civil war.

But the accelerating exodus from Syria's bloodshed means that the number of Syrians seeking help in Lebanon is growing by 3,000 a day, leaving authorities and the UNHCR refugee agency struggling to provide for them.

"We have this very tiny country ... a quarter of the size of Switzerland, with a population of 4 million people, taking in 260,000 refugees," UNHCR representative in Lebanon Ninette Kelley told Reuters late on Friday.

"I think what we need to start doing is to prepare for an eventuality whereby we may not be able to find enough shelter and accommodation given the current level of demand."

"We have advised the government that it may be a time to start having at least two transit sites," she said, where refugees could be offered temporary food and shelter before other accommodation is found. "As a start, that would be a good thing."

UNHCR has also made contingency plans to establish formal refugee camps if the mass influx continues, though that would have to be with Lebanese government permission, she said.

"We do plan for camps. We pre-position stocks, we make sure we have done assessments and that we are ready to go in that eventuality," she said in an interview at UNHCR headquarters in southern Beirut.

Reluctance to set up refugee camps stems in part from historic sensitivities over the waves of Palestinian refugees who fled from Israel, some of whom became central players in Lebanon's destructive civil war.

The issue also highlights the country's current political divide. Some of Syrian President Bashar al-Assad's Lebanese foes openly called for camps to be set up, hoping it would highlight the scale of his crackdown on the nearly two-year-old uprising in which an estimated 60,000 people have been killed.

The government of Lebanese Prime Minister Najib Mikati, dominated by Assad allies including Hezbollah, preferred to support aid efforts to house the refugees in homes and schools in their own Sunni Muslim communities.

Aid workers say that the political concerns constrained their ability to help during the first year of the conflict, particularly in Lebanon's Bekaa Valley, where pockets of Christians, pro-Hezbollah Shi'ite Muslims and Sunni Muslim supporters of the armed Syrian rebels live close by.

They are still struggling. A report by the French aid group Medecins Sans Frontieres said half the refugees in Lebanon were not receiving sufficient medical care and many more were living in inadequate winter shelter.

UNHCR has increased registration of new refugees to 40,000 a month, but even that may not keep pace with new arrivals and its capacity is stretched to the limit.

Kelley said that despite last month's U.N. conference in Kuwait, when $1.5 billion was pledged for Syrian humanitarian aid, U.N. operations inside Lebanon had so far only received 15 percent of their funding requirements.

"Our problem right now is we simply don't have enough funds to do 100 percent coverage of registered refugees and all the new arrivals," she said.-Reuters