DHAKA (AFP) - Sixteen Bangladeshi border guards accused of taking part in a mutiny have died in custody, the military acknowledged Thursday, while insisting the deaths were the result of suicide or illness. The New York-based Human Rights Watch group, which has demanded an investigation into alleged torture of the 1,000 detained soldiers, questioned the official account of how the men died. Four of the deaths which all occurred between March 9 and April 16 were suicides, six were a result of heart attacks and six died of other diseases, the Bangladesh Rifles (BDR) said in a statement. The soldiers have been detained for questioning since the two-day revolt in Dhaka in February, when scores of officers were killed by their men. Some of the BDR soldiers connected with the mutiny are committing suicide which is quite unexpected, the BDR statement said. We believe that perhaps they have failed to cope with the mental pressure associated with the guilt of committing the brutal attacks. Suicide is seen as a sin in religious terms and is also socially undesirable. Brad Adams, Asia director of Human Rights Watch, told AFP that the official causes of death were questionable. I have never heard, in all of the countries I have worked in, of so many deaths in custody in such a short period of time, he said. There is no reason to believe at face value any of these deaths are from natural causes or suicide. We are extremely concerned about ongoing torture and lack of access to the detainees. During a hearing on Wednesday related to the mutiny, one soldier alleged in court he had been tortured while in custody, according to the online newspaper bdnews24.com. Findings of a government inquiry into the mutiny are yet to be made public, after several delays over the past month. The BDR said on Thursday that a programme of motivational activities was planned to prevent further suicides.