Police said they were negotiating with the group as experts warned of soaring economic losses from the blockade.

Some 100,000 passengers remain stranded in Bangkok while efforts are being made to find alternative airports.

Meanwhile, thousands of government supporters held their first rally in the capital since the blockade began.

Fears of clashes between pro- and anti-government groups have grown since a new grenade attack on opposition supporters in Bangkok on the night of Nov. 29, which injured about 50 people, three of them seriously.

Police say they want to avoid any violent confrontation and will not use weapons against the protesters at the capital's international and domestic airports.

Some travellers have been trying to get to smaller airports around the country, but these are being overwhelmed.

More than 450 Muslim pilgrims stranded at the international airport were taken by bus to the base on Nov. 30 where they were to board a plane for the annual Hajj in Saudi Arabia.

Thailand's tourist industry is losing an estimated US$85 million per day, and the government warns that the number of foreign tourists arriving next year may halve, threatening one million jobs.