The alleged mastermind behind an Islamic insurgency in southern Thailand, arrested last week in Malaysia, holds Thai citizenship and Bangkok will seek his extradition, Thai officials said today.

Foreign Minister Surakiart Sathirathai told reporters before a cabinet meeting that Thailand would give the Malaysian embassy evidence that the suspect was a Thai national and that two countries had signed a treaty that would allow for his extradition.

"We have firm evidence that he is a Thai national," he said.

"Thailand's position is that we have had an extradition treaty since 1911, and that the agreement has since been reaffirmed," most recently last year, he said.

Malaysian Prime Minister Abdullah Ahmad Badawi has said the man was a Malaysian citizen, and that the two countries did not have an extradition treaty.

Malaysian or Thai?

Thai Prime Minister Thaksin Shinawatra told reporters the man appeared to hold dual Thai-Malaysian citizenship, which is not allowed under Malaysian law.

"Under Malaysian law, they do not allow dual citizenship, so he will have to renounce one. We have to discuss this with Malaysia based on the evidence we have," he said.

Thai authorities had listed Chae Kumae Kuteh, also known as Doramae Kuteh, as the nation's most-wanted man, blamed for masterminding the raid on an army depot on Jan 4, 2004, which ignited an Islamic insurgency in southern Thailand.

Surakiart said international law experts from both nations would meet to determine whether the suspect could be extradited to face charges in Thai courts.

Malaysia said last Thursday it had arrested a man identified as Abdul Rahman Ahmad, also known as Deraman Koteh, who was believed to be the man sought in Thailand for the depot raid.

The Islamic insurgency in southern Thailand has become a thorn in relations with Malaysia, and last week's arrest sparked a minor war of words.

Largely Muslim Malaysia has been irritated by Thaksin's past remarks about the alleged cross-border movements of Thai Muslim militants, many of whom share a kinship with Malays in its own northern states.