LUCKNOW, India: A leading international human rights group on Tuesday called for Indian police to be punished for torturing Muslim men detained after last year’s bomb attacks in a southern city.

According to the New York-based Human Rights Watch (HRW) police officers allegedly tortured 21 Muslim men during an investigation into a series of bombings.

Bomb attacks in Hyderabad, the capital of Andhra Pradesh state, in May and August last year killed more than 50 people.

"The detainees were stripped, hung upside down, severely beaten, subjected to electric shocks, and otherwise ill-treated," the group said in a statement. "They were also threatened with the torture of their relatives, particularly female relatives."

The rights group said evidence of the torture was gathered from the testimony of the men and findings of the state Minorities Commission that concluded that several of them sustained injuries while in custody.