BANGKOK: Hundreds of anti-government protesters rallied in Bangkok Thursday, hours after a bomb injured ten people and heightened fears that political tensions in Thailand were again spiraling towards violence.

Ten volunteer security guards for the People's Alliance for Democracy (PAD) were hurt when a small bomb was tossed into their protest camp near the regional UN headquarters in Bangkok.

A grenade was also thrown at a judge's house and a man was found shot dead near the protest site where PAD supporters have been holding rallies since late May in an effort to bring down the government.

They claim the People Power Party, which was elected in December last year, is running the country on behalf of ousted prime minister Thaksin Shinawatra, whom they accuse of corruption and nepotism.

Captain Pompetch Chotklang of Bangkok's police said two PAD supporters were in a critical condition after the attack near the UN office, carried out before dawn by two unidentified people on a motorcycle.

"Six people were hospitalised and four who sustained minor injuries received medical treatment by the PAD," Pompetch told AFP.

PAD supporters have been occupying the grounds of the prime minister's offices in Bangkok's historic district since late August.

It was the smaller, original protest camp at an intersection called Makawan Bridge near the UN regional headquarters that was attacked on Thursday.

The PAD immediately blamed government supporters for the blast, which came less than a month after bloody street battles between protesters and police left two people dead and nearly 500 others injured.

"The army should send in its security team to protect innocent people, otherwise they are ignoring their duty as protesters are struggling to protect the monarchy," PAD leader Chamlong Srimuang said on the group's website.

In a separate incident, someone hurled a grenade at the home of Constitutional Court judge Jaran Pakditanakul, causing no injuries.

A 46-year-old man was also shot dead near the Makawan Bridge protest camp, police said, although it was unclear if his death was related to the ongoing political turmoil.

Meanwhile up to 1,000 PAD protesters set up steel barricades and stopped traffic outside the British embassy to demand Thaksin's extradition.

The multi-millionaire and twice-elected Thai premier fled to London in August, two months before he was sentenced in absentia to two years in jail for violating the kingdom's corruption law.

"Why doesn't England send Thaksin back to Thailand to be put in jail?" PAD spokeswoman Sarocha Pornudomsak shouted to the crowd.

The crowd carried placards of Thaksin and his wife Pojaman saying "Wanted for crimes against the kingdom of Thailand”.

About 120 police with shields stood guard, but the crowd -- as usual swaddled in yellow t-shirts to show their loyalty to the Thai monarchy -- appeared calm and relaxed, witnesses said.

After handing over a letter urging Britain not to grant Thaksin political asylum and to send him home, they began to a march through a key tourist area.

PAD protests in early 2006 helped lead to the coup that overthrew Thaksin later that year, and the return to power of his allies angered the PAD and the old power elite in the palace, military and bureaucracy.

Prime Minister Somchai Wongsawat -- Thaksin's brother-in-law -- has been under increasing pressure to resign since the bloody October 7 clashes.

Earlier this month the heads of Thailand's armed forces strongly hinted that Somchai should step down, and on Thursday Air Force chief Ittaporn Subhawong urged the premier to protect Thai citizens.

"The government must effectively enforce the law, to prove that the government is able to protect people's lives and property," he told reporters.

Pro-government supporters have vowed to hold a massive rally at a stadium on Saturday, which Thaksin is expected to address by telephone.

- AFP/yt