The man was visiting a Thai friend, who was also killed in the attack.

The Army said it was "unusual" for suspected insurgents to target Malaysians.

Army chief General Sonthi Boonyaratglin has launched a special investigation.

Tak Bai district village head Chairoj Jehlae, 54, died in the suspected Islamic militant gun attack, along with Malaysian Jeh Ayub bin Yacob.

The two were driving a car between Tak Bai and Sungai Kolok, a border district.

Details concerning the Malaysian were unclear, but police said he was a resident of Kota Baru in Malaysia's northern state of Kelantan.

Sonthi said the gun attack on a Malaysian citizen was "abnormal and rare".

"General violence in the deep South should not happen like this. It looks like a personal conflict, but let officials investigate this," he told reporters.

Meanwhile, local authorities were yesterday on alert following intelligence reports that the separatist group Gerakan Mujahideen Islam Pattani (GMIP) - also known as the Pattani Islamic Mujahideen Movement - would launch attacks from today to next Wednesday to commemorate its establishment in the 1980s.

Sonthi said he did not expect large-scale attacks but ordered a state of alert anyway.

As many as 3,000 sympathisers and supporters of the group were expected to gather at a central Yala mosque today.

An estimated 1,700 people have died in the region since violence erupted in January 2004. The government blames Islamic separatists. No group has claimed responsibility for the killings.

Sonthi said security officials were struggling to contain the unrest because of changing militant tactics.