Security forces have killed more than 100 suspected Muslim militants today during the most violent clashes yet in volatile southern Thailand. Five security force personnel were also killed in the fighting.

In a highly co-ordinated 5am (2200 GMT) attack, the teenagers stormed more than 15 police bases, village defence posts and district offices in Yala, Pattani and Songkhla provinces, apparently to try to steal weapons.

But the security forces were tipped-off in advance and sat in waiting for the assailants, most of whom were wielding machetes.

Lieutenant General Proong Bunphandung, the chief of police for the south, said: "The security officers have been patiently working with local people and gathering intelligence. We waited for the right time to achieve this success," he said.

However the fighting went on for eight hours, ending when police fired tear gas and bullets into the historic Kreasae mosque outside Pattani, killing 34 suspected militants who were holed up inside.

Sunai Phasuk, a spokesman for Thai human rights group Forum Asia, said that the mosque held major significance for Muslims across Southeast Asia.

"We had been in communication with the government before noon and had urged them to be very careful with that mosque," he said, adding that imams had been on stand-by and prepared to act as negotiators. The blood-soaked bodies were unceremoniously thrown into pick-up trucks to be taken for forensic examination.

The Government has blamed the attacks on Islamic separatists seeking to carve out a homeland in the Muslim-majority south of a predominantly Buddhist country.

"Most of the dead insurgent are youths of ages ranging from 15 to 20, but two of the leaders are aged about 50 and 60," said General Proong Bunphandung.

Army General Chaiyasith Shinawatra told reporters that 107 insurgents were killed and 17 were arrested. Three police officers and two soldiers were also killed while 15 police were wounded.

It was the bloodiest day in the south where almost daily attacks by gunmen had left nearly 160 people dead this year. Many parts of the region have been under martial law for months.

Television news reports showed the bodies of insurgents lying in pools of blood, some of them in front of police stations still clutching their machetes and wearing camouflage.

Elsewhere in the troubled region, trucks disgorged dozens of soldiers in combat gear to reinforce the already extremely tight security presence.

Authorities sealed off roads leading to the attacked checkpoints and police stations.

Security was tightened along the border with Malaysia, which has in the past denied allegations of harbouring militants.

Police said that the raids were linked to an attack on a military camp in January in the nearby Narathiwat province, which triggered an upsurge of violence in the area this year. Four soldiers were killed and hundreds of guns were stolen in that raid.

However Thaksin Shinawatra, the Prime Minister, denied that the attackers had connections to international terrorists. "Most of the insurgents are youths from the southern provinces," he said.

"Their acts are not linked with international terrorists." He said that they intended "to rob guns from defence volunteers and district offices, but our troops were well prepared for that."

Muslims have long complained of discrimination in jobs and education in Pattani, Yala and Narathiwat, Thailand's only Muslim majority provinces.

They also say that their culture and language are being subjugated by the Buddhist Thais, and cite as an example the state schools, which teach in the Thai language.

Muslims in the south speak Yawi, a dialect of Malay.

The alienation caused by the Government's policies has been the source of a decades-old separatist struggle, which had subsided after an amnesty in the late 1980s before exploding this year into a frenzy of violence with the army arsenal raid in January