Thailand has freed six Malaysian soldiers who were detained after they mistakenly crossed into Thai territory during a military exercise, an official said Saturday.

"They were released on Tuesday. They are in good health. The Thais know it was a mistake," a Malaysian defence ministry official told AFP .

The official Malaysian Bernama news agency said six Malaysian soldiers had crossed into Bukit Tokmok in the troubled southern Thai province of Narathiwat on Monday.

The six were detained at Senanarong Army Camp in Songkhla in Narathiwat for questioning.

Diplomatic row

More than 1,000 people have been killed in Thailand's three Muslim-majority provinces bordering Malaysia since an Islamic insurgency broke out there in January 2004.

A group of 131 Thai Muslims fled across the border last year citing fear of persecution by Thai security forces fighting the insurgency.

The group's flight triggered a diplomatic row between Thailand and mainly Muslim Malaysia, which insisted that they should not be forced to return - particularly if their safety could not be assured.