The Thai army said today it had detained 342 Muslims in raids in the rebellious far south.
Human rights group criticised the move, one of the largest series of arrests in more than three years of separatist violence, saying it exposed detainees to potential abuses by the army. The military operates under martial law that grants soldiers immunity from prosecution.
The detainees were taken for questioning to five army camps across the four southern provinces where more than 2,300 people have been killed in the three-year insurgency.
A army spokesman said the prisoners, who can be kept without charge for 28 days under emergency security laws, would be freed if found not to have been involved in the violence.
Samples of their DNA would be kept on record.
Since taking office last year following a bloodless coup, Prime Minister Surayud Chulanont has fought off pressure from Thailand's Buddhist majority to take stronger action in the Muslim, Malay-speaking region, saying he remains committed to a peaceful resolution.