Malaysia has detained 19 Thais in northeast Kelantan state, with police saying that they are economic migrants rather than refugees fleeing violence in Thailand's restive south.

The 19, who include five children, were arrested at roadblocks on Kuala Lumpur-bound buses during a four-day operation in Kelantan, which borders Thailand, district deputy police chief Mat Nasir Hussein told AFP.

The New StraitsTimes on Tuesday quoted an unnamed source as saying they were believed to have crossed the border to escape violence in Thailand.

But Mat Nasir refuted the report saying: "They are not refugees. Not all of them are Muslim or from the south of Thailand. We believe they came to Malaysia to seek illegal employment."

He said only four of the Thai nationals were Muslim and the rest were Buddhists, adding that they would be charged with not possessing valid travel documents.

Temporary shelter

A total of 131 Thai Muslims crossed into Kelantan late last month, saying they feared for their lives in the restive south of the country.

Mainly-Muslim Malaysia has given them temporary shelter pending an investigation of their status and reasons for leaving, but has voiced concern over the prospect of more fleeing across the border.

Nearly 900 people have been killed in the past 20 months in Thailand's southernmost provinces, in attacks which analysts and authorities blame on Islamic separatists, organised criminals and drug dealers.