Arbitrary arrests and prisoners dying from disease, malnutrition and torture -- Amnesty International accused Cameroon of rights abuse during its battle to clear the far north of Nigeria's Boko Haram Islamists.
"In seeking to protect its population from the brutality of Boko Haram, Cameroon is pursuing the right objective; but in arbitrarily arresting, torturing and subjecting people to enforced disappearances the authorities are using the wrong means," Amnesty's regional director Alioune Tine said in a statement.
A report by the rights group said more than 1,000 people accused of supporting Boko Haram were currently detained in desperately overcrowded prisons lacking food and water.
In Maroua prison for example, poor conditions were causing the deaths of six to eight people each month.
And more than 100 people had been sentenced to death in Maroua's military court in the past year, though none had yet been executed.
Amnesty said it had documented the cases of 29 people tortured by security forces between November 2014 and October 2015, six of whom subsequently died.
A source close to the government who asked not to be identified said "we reject this report".
"Amnesty International knows that we have lost more than 2,000 people (killed by Boko Haram)," the source added.
More than 8,000 Cameroonian soldiers are currently deployed in the far north, where Boko Haram fighters from across the border have carried out repeated attacks over the last three years.
