Amnesty International says Nigeria's police and military routinely torture women, men and children as young as 12 with beatings, shootings, rape, electric shocks and pliers used to pull out teeth and nails.

A new report Thursday collated from hundreds of testimonies gathered over 10 years says most of those detained are denied access to family or lawyers.

Amnesty says torture has become so institutionalized that many police stations have an informal "officer in charge of torture" or OC Torture.

Amnesty's Africa director Netsanet Belay said the indiscriminate roundups of hundreds of suspects who were tortured in a "screening" to find Islamic extremists is more like a "medieval witch hunt."

Nigeria's government and military have responded to previous Amnesty International reports of abuses with promises to investigate.