Some of the Islamic militants suspected of waging a year-long separatist insurgency in southern Thailand were trained in neighbouring Malaysia, Thai Prime Minister Thaksin Shinawatra said today.

Thaksin also identified a fugitive Islamic school principal as the likely mastermind of the separatist movement in the kingdom's Muslim-dominated deep south, where violence has claimed more than 560 lives this year.

"If you ask me where they have been trained, absolutely one group of them has been trained in Malaysia, but we believe it was done without the knowledge or support of the Malaysian government," Thaksin told reporters.

"They were trained in the jungle of Kelantan state in Islamic schools there," he said.

Thaksin has described the violence as part of a "homegrown" separatist movement, though he has also expressed concern that some Muslim activists seek shelter in Malaysia.

Kelantan is the only one of Malaysia's 13 states which is ruled by the opposition Islamic party PAS, and shares a border with the southern provinces of mainly Buddhist Thailand.

Chaotic riot

Earlier this month a Malaysian lawmaker charged that the outlawed Pattani United Liberation Organisation, which is fighting for a separate Islamic state in southern Thailand, had been given RM120,000 by the Kelantan state branch of the Malaysian Islamic Welfare Organisation.

Malaysia said it does not support the separatist movement.

The two governments have vowed stronger cooperation, particularly in detecting and stopping the cross-border movements of militants.

"But because we have a common border, people can cross freely," Thaksin said. "Some people have relatives on either side of the border and that's why Malaysians were furious about the case of Tak Bai."

Thai security forces quelled a chaotic riot in the southern town of Tak Bai in October and at least 87 protesters died, mostly in custody when they were bound and piled into military trucks.

On Thursday Thai authorities announced they had detained four Islamic teachers suspected of masterminding "terrorism" in the violence-racked south. They were brought to Bangkok Friday to appear in court.

A fifth suspect, Islamic school principal Sapae-ing Baso who evaded capture, was fingered by Thaksin Friday as the likely ringleader.

"From the interrogations it has become clear that he, Sapae-ing, is the leader of the movement," Thaksin said.

The premier said security forces were targeting another 100 key figures for arrest, most of whom he described as separatists.