Amnesty International on Tuesday demanded the immediate release of five Indian activists jailed in southern Mexico on suspicion of homicide, calling them "prisoners of conscience."

"All five are innocent of the murder charges and their detention and prosecution is politically motivated," the London-based rights group said in a news release.

The five, arrested in April, belong to the Organization of the Tlapaneco Indian People, an activist group that has protested army patrols and forced sterilization of some men in their remote mountain communities in the 1990s.

They were detained in connection with the killing of a government supporter in January in the mountain community of El Camalote. Leftist rebel groups and drug traffickers have been active in the Pacific coast region over the past decade.

A court ruled in late October that there was not enough evidence to continue holding the five men, but federal prosecutors appealed that ruling, guaranteeing the men would remain in jail.

The federal Attorney General's Office said it had no immediate response to the Amnesty International statement.

Vidulfo Rosales, a lawyer representing the men, said the continued prosecution of the men was aimed at quashing the protest movement. "What they want to do is to decimate and disband this organization," Rosales said.

In June, Guerrero state authorities agreed to pay 35,000 pesos ($3,400 at the time) in compensation to 14 indigenous Mexican men coerced into having vasectomies, and give them water storage tanks and cement to build homes.

But Rosales said other parts of the compensation agreement — punishment for the authorities who coerced the men into the procedure, and the construction of rural health clinics — have gone unfulfilled.