Thai protestors forced riot police to abandon a checkpoint yesterday, tightening their grip on the country's main airport in a bid to push the elected government from power.

Around 2,000 People's Alliance for Democracy (PAD) supporters forced 150 police to retreat 1km (0.6 miles) north of Suvarnabhumi Airport, but the incident passed without violence.

The protestors are seeking to oust Thai prime minister Somchai Wongsawat, who is running the country from the government's stronghold in the northern city of Chiang Mai.

Thailand's chief of police has been sacked as hundreds more protestors descended on Bangkok's main airport to reinforce a five-day anti-government blockade, threatening to "fight to the death" if police tried to remove them.

Wongsawat sacked his national police chief, General Patcharawat Wongsuwan, yesterday after his failure to lift the siege by force on Thursday. "The removal was the result of his performance during this crisis," said a government spokesman.

By early evening, 80 riot police with truncheons and shields gathered in a car park near the main terminal building. But their numbers were dwarfed by the 6,000 or so protestors inside, some armed with baseball bats, iron bars and other makeshift weapons.

"We will not leave," said Suriyasai Katasila, leader of the People's Alliance for Democracy (PAD). "We will use human shields against the police if they try to disperse us."

But the authorities cannot let the protest drag on. As long as the stand-off continues, not only are thousands of tourists stranded, air freight has ground to a halt and serious damage is being done to Thailand's economy. Officials and economists project the tourism industry's losses over the rest of the year will rise to 150bn baht (€1.9bn), equal to 1.5% of the country's GDP.