The government today cast doubt on allegations that the prime suspect behind two days of violence in southern Thailand had dual Thai-Malaysian nationality and had crossed into its territory.

Foreign Minister Syed Hamid Albar said the Malaysia-Thailand border was "very well secured" through close co-operation between security forces in the two countries.

"They do monitor the situation and we co-operate quite closely with Thai authorities. If we find anybody, we will take whatever necessary measures. We don't welcome bandits in our territory," he told reporters.

Four Thai soldiers were killed on Sunday during an arms heist by dozens of assailants as 18 schools were set ablaze, while on Monday martial law was declared in some districts after two bomb blasts killed two policemen.

Thai police chief General Sant Sarutanond identified the prime suspect behind the violence as a "local troublemaker" with dual Thai-Malaysian citizenship who had fled across the border.

"I want to make it very clear that under our law, we do not recognise dual nationality," Syed Hamid said.

"A person cannot be a national of one country and a national of Malaysia. If a Malaysian acquires a nationality of another country, then he will lose automatically his Malaysian nationality."

Outside influences

Thai Foreign Minister Surakiart Sathirathai would meet Prime Minister Abdullah Ahmad Badawi in Malaysia's administrative capital of Putrajaya later today to brief him on the flare-up, Syed Hamid said.

Thai Premier Thaksin Shinawatra has blamed the assault on bandits involved in arms smuggling but has also warned that outside influences were at work, citing Islamic militants, although he denied the gunmen were linked to Thai Muslim separatists.

"There are connections with the outside, from Aceh (the restive Indonesian province)," Thaksin said. "The bandits are involved with Thailand and Malaysia .... Some of them are tied to mujahidin."

Syed Hamid said there was no need to overreact to the violence by issuing an advisory warning Malaysians against travelling to southern Thailand.

"I don't think there should be any travel advisory. Malaysians should keep a close watch on what is happening there. I think generally the situation in Thailand is under control and that they are handling the situation well," he said. - AFP