Malaysian troops on the border with Thailand have been put on alert in response to the violence that has flared in Thailand's Muslim-majority southern provinces, officials said.

Defence Minister Najib Razak told the official Bernama news agency that the measure was taken to prevent Thai militants from intruding into Malaysia and using its territory as a base to mount attacks in Thailand.

The security forces would also be looking out for Thais attempting to sneak across the border into Malaysia to escape the unrest, he said.

Field commander Lieutenant General Masood Zainal Abidin told Bernama that the army had deployed three battalions to the border as part of efforts to prevent the illegal entry of Thais.

"The three battalions of the army is sufficient to ensure security along the Malaysia-Thai border," he said.

Asked to comment on the brutal killing of two Thai servicemen who were taken hostage in a Muslim village Wednesday, Najib said the Malaysian government could only monitor developments in the region.

"We have not been able to do anything because it is a conflict happening in a neighbouring country and we need to respect Thailand's sovereignty," he said.

Cannot guarantee safety

The hostage crisis was widely reported here, particularly because Malaysian journalists were taken to the scene by the Thai military, reportedly to act as intermediaries. However the servicemen were killed before they arrived.

Najib said the Malaysian government could not guarantee their safety of media personnel who crossed the border to report on the unrest.

The Muslim insurgency in southern Thailand, where more than 940 people have died in near-daily shootings, bombings and arson attacks since the start of last year, is becoming an irritant to relations between the neighbours.

Tensions flared earlier this month when 131 Thai Muslims fled across the border, seeking sanctuary in several mosques and saying they feared for their lives.

The United Nations refugee agency has interviewed the 131, over the objections of the Thai government, to determine if they qualify for UN protection.