A group of men who were originally charged with running an armed “terrorist” group and now stand accused of conspiring to topple the Cambodian government have been tortured and held illegally, lawyers and a minority rights group said yesterday.

Ang Chanrith, director of the Minority Rights Organization (MIRO), said the three Khmer Krom and four Cambodian nationals, some of them monks, will stand trial tomorrow accused of “providing a foreign state with means to undertake hostilities and aggression”.

“Two of seven were tortured and forced to confess in police custody,” Chanrith said of two of the Khmer men.

The men – Yong Kim Srun, 27; Yean Yeap, 25; Thach Koung, 37; Khe Ma, 28; Thach Keu, 52; Yin Yav, 55; and Soun Thol, 56 – were arrested in Thailand in March 2013 and stand accused of creating an armed terrorist group.

According to MIRO, this charge “could not be upheld” and was changed to “delivering equipment for national defence to a foreign state.” It was later altered to the charge of “conspiracy”.

“MIRO believes that these repeated modifications of charges signify the lack of credible proof for an existing criminal offence,” a statement released yesterday said.

Chanrith said that four of the men are also charged with illegally crossing the border.

“How can they be charged for crossing into Cambodia? They are Khmer,” he said.

Sam Sokong, a defence lawyer for two of the Khmer Krom detainees, Kim Srun and Thol, said his clients have been illegally detained.

“Although there is a procedure that the court may detain them longer than six months, [by law], we [the lawyers] should have been informed. I have not received a letter from the court,” he said.

The defendants are members of Denmark-based dissident group the Khmer National Liberation Front.

According to Sokong, six others accused under the same charges, including KNLF president Sam Serey, are at large.

When asked last night about the charges, Serey said “what the government says is not true” and he and his “5,000 members” simply “campaign for freedom and democracy”.

“I have [just] tried to create a network to help change the policies of the government,” he said, adding that he has no plans to return to Cambodia to face the charges.