At least five people were injured when protesters opened fire on government supporters as part of efforts to topple the administration, which critics claim is a corrupt proxy for the country's ousted prime minister.
Anti-government protesters blockading the Thai premier's temporary offices and Bangkok's main airport opened fire on rival activists Tuesday, wounding at least five people, police said.
The violence erupted on the road to a disused air terminal where thousands of demonstrators behind a six-month street campaign have surrounded the makeshift headquarters of premier Somchai Wongsawat.
Separately, anti-government protesters clad in yellow clothes that symbolise their loyalty to the revered monarchy tried to blockade the main Suvarnabhumi international airport ahead of Somchai's return from a trip abroad.
"Five supporters of the government have been wounded from gun shots by PAD (People's Alliance for Democracy) who were on a pickup truck," a senior Metropolitan police officer told AFP on condition of anonymity.
Television footage showed at least one man in a pickup truck opening fire on an unarmed group, before men in yellow shirts got out and beat them with white poles, as fires burned in the background.
The PAD -- a coalition of royalists, Bangkok's old elite and the middle class -- accuses the government of being a corrupt puppet of exiled former premier Thaksin Shinawatra.
Thaksin, who is Somchai's brother-in-law, was ousted in a 2006 coup.
Somchai rejected calls to quit, while the government insisted that a key cabinet meeting would go ahead on Wednesday at an undisclosed location to prevent further protests.
"Anyone who wants to overthrow or resist the government is attempting a rebellion," Somchai told the Thai National News Agency on board a flight from an APEC summit in Peru.
The Thai army chief meanwhile dismissed protesters' calls for the military to step in as it did two years ago.
"The armed forces have agreed that a coup cannot solve our country's problems and we will try to weather the current situation and pass this critical time," army chief General Anupong Paojinda told reporters.
A day after PAD protests forced the cancellation of a parliamentary joint sitting, about 10,000 demonstrators moved to the old Don Mueang International Airport early Monday to shut off Somchai's current base.
Protesters have already occupied the prime minister official office and cabinet headquarters at Government House in Bangkok since August.
Riot police largely withdrew on Monday amid fears of a repeat of clashes between protesters and police on October 7 that left two people dead and 500 injured, the worst political violence in Thailand for 16 years.
"There are more than 10,000 of us here and we are prepared for a long siege like at Government House," said Sawit Kaoewan, a PAD leader. Police confirmed the figure.
About 1,000 demonstrators later moved to the new Suvarnabhumi international airport in a bid to block Somchai's return from a trip abroad, airport authorities told AFP.
They said there was no disruption to the handful of domestic flights that operate from Don Mueang or to services at Suvarnabhumi, which took over as Bangkok's main airport two years ago.
Hundreds of PAD supporters also went to the nearby military headquarters after speculation that the cabinet would meet there with Somchai on Wednesday.
Government-run corporations said there was no response to a strike call by Thailand's main public sector union.
The protests spread a day after the PAD blockaded parliament in what they called a "final battle" in their six-month campaign against the administration.
The PAD, which also launched huge street protests in 2006 that led to the Thaksin coup, called this week's rallies in response to a grenade attack on Thursday that killed one protester.
Billionaire Thaksin fled Thailand in August this year to avoid corruption charges, but has said in an interview that he wants to return.
"With me at the helm I can bring confidence quickly back to Thailand," he told Arabian Business magazine in an interview published Sunday on its website.
Date created : 2008-11-25