BANGKOK • Rights groups yesterday urged the Thai army to drop defamation charges against three activists over a report on torture in the conflict-hit south, decrying the prosecution as an effort to silence critics.

A state prosecutor was handed the case file yesterday and will now decide whether to press on with the controversial charges against Pornpen Khongkachonkiet, Anchana Heemmina and Somchai Homlaor.

Pornpen is the Amnesty International Thailand chairman, while Anchana is the founder of the Duay Jai Group which provides rehabilitation services for torture victims. Somchai is a human rights lawyer.

The trio could face up to seven years in jail for defamation and a separate charge filed for publishing the report online.

Released last year, the report, which is based on interviews with 54 former detainees, catalogued a host of torture tactics allegedly used by soldiers and police across the kingdom's Muslim-majority southernmost provinces.

More than 6,700 people have been killed in an almost 13-year insurgency by Malay Muslim locals against the Thai state, which rules the region with emergency laws.

Beatings, threats at gunpoint, sensory deprivation and partial suffocation were all routine during detention of suspects, the report alleged.

The Thai army denied the allegations and launched proceedings against the report's writers.

"We will not withdraw the charges," Colonel Yutanam Petchmoang said, adding that the rights workers "did not cooperate" when they were summoned by the military and asked to name the soldiers accused of torture in their report.

Mr Sunai Phasuk, a Human Rights Watch representative for Thailand, said the defamation case "is a glaring example of the Thai military misusing the criminal justice system to intimidate and retaliate against activists for reporting grave abuses".

AGENCE FRANCE-PRESSE