Malaysia today criticised Thai Prime Minister Thaksin Shinawatra for telling reporters that he wanted an alleged Muslim separatist extradited from Malaysia, saying he should have followed diplomatic channels.

"This is not the way to cooperate with each other," Foreign Minister Syed Hamid Albar told a news conference when asked about Thaksin's statement that Thailand's most-wanted man had been arrested in Malaysia.

"We can't react to a news report. Whatever it is that needs to be done, there are proper channels between Malaysia and Thailand," Syed Hamid said testily.

"If they use the proper channels then Malaysia would react accordingly. There are rules pertaining to extradition."

Asked whether he could confirm the arrest, he replied: "No."

"If Thailand wants to know about any arrest they should contact their counterparts. It should not be done in ... requests through the media."

Thaksin said earlier that Malaysia had arrested Doramae Kuteh, also known as Chae Kumae Kuteh. He is alleged to be the mastermind behind a January 2004 arms depot raid that reignited unrest in Thailand's Muslim-majority south which has left at least 570 people dead.

"Absolutely we want him extradited back here as he has been involved with many incidents. He has been the real mastermind (behind the unrest) including last year's robbery of government-owned weapons," Thaksin told reporters.

Alleged militant held under ISA

Thaksin did not elaborate on how and when the suspect was arrested but said he was captured alone and detained under Malaysia's Internal Security Act, which allows suspects to be detained without trial, for also posing a threat there.

"We are coordinating with Malaysia to determine his nationality, but initially we will take part in investigations and we are now checking for evidence as well as on his Thai nationality," the Thai premier said.

Doramae Kuteh is wanted in Thailand for premeditated murder and inciting a guerrilla movement and had a bounty of five million baht (about US$130,000) on his head.

He reportedly fled to Malaysia after the arms depot raid in which attackers killed four soldiers and stole hundreds of rifles.

This is not the first time that Malaysia has been irritated by Thaksin's remarks about the alleged cross-border movements of Thai Muslim militants, many of whom share a kinship with Malays in Malaysia's northern states.