Malaysia will beef up security along its border with Thailand to prevent any illegal intrusion, Deputy Prime Minister Najib Razak said Saturday after a top military official reported of alleged spying.

"We will deploy additional security forces to prevent any intrusion into our territory. We will not allow anyone to enter our territory to gather intelligence. They have to respect our borders," Najib, who is also defence minister was quoted as saying by Bernama news agency.

Defence forces chief Mohamed Anwar Mohamed Nor on Friday said soldiers guarding the border in Kelantan had seen men in black balaclavas, believed to be Thai military personnel trying to monitor troop movements at the Malaysian border post.

"A preliminary report found that on September 17, the spies were seen climbing trees to look across the border," he said.

Najib said the situation at the border was calm.

"We do not want any new incident that may sour Malaysia-Thailand relations," he said.

Working together

Relations between the southeast Asian neighbours have deteriorated since 131 Thai Muslims from southern Narathiwat province crossed the border in August, saying they were fleeing separatist unrest, and triggering a tussle over the fate of the group.

Najib said Malaysia and Thailand were working together to resolve the issue, adding that he would meet Thai Deputy Prime Minister Chidchai Vanasathidya here on October 28 to discuss their status.

Thai Prime Minister Thaksin Shinawatra has asked Malaysia to hand over suspected militants believed to be among the group, which includes women and children.

Nearly 1,000 people have died in unrest in Thailand's mainly Muslim provinces bordering Malaysia since January 2004.

Analysts and authorities blame the almost daily attacks in the region on Islamic separatists, organised criminals and local corruption.