Turkey has arbitrarily detained and tortured hundreds of people, including soldiers and high-ranking military officers, Amnesty International said on Sunday.
More than 13,000 people have been detained as part of a crackdown led by President Recep Tayyip Erdogan in response to the July 15 failed military coup, which left 260 people dead.
Of those detained, 6,000 have been placed under arrest.
Citing interviews with lawyers, doctors and one person on duty in a detention centre, Amnesty said there is evidence pointing to acts of torture, rape, sexual assault, abuse and denial of food and medical treatment in detention centres, where people are held without access to lawyers.
The group warned that new measures under the state of emergency will allow detainees to be held for up to 30 days without being charged, and place constraints on judicial proceedings - such as a detainee's right to choose a lawyer. In many cases, Amnesty said, denial of such rights amounted to enforced disappearance.
"Detaining people in connection with a criminal charge without demonstrating that you have evidence of criminal wrongdoing is by definition arbitrary and unlawful," Amnesty's director for Europe, John Dalhuisen, said in a statement.
The report was published amid rising concern among Turkey's allies over the rapid pace of institutional closures and sackings.
Specific accounts relayed by Amnesty include reports of 650-800 soldiers being held in the police headquarters of Ankara, judges being detained in the corridors of courthouses, and facilities like sports centres and stables being converted into detention sites.
It also heard accounts of 300 soldiers showing signs of having been beaten, including 40 who were so badly injured that they could not walk and two who could not stand up, and senior military officers raped with truncheons.
"The grim details that we have documented are just a snapshot of the abuses that might be happening in places of detention," Dalhuisen said.
Amnesty called for the European Committee for the Prevention of Torture (CPT) to immediately conduct an emergency visit to Turkey, asked Turkish authorities to condemn torture, and called for monitors to have access to detention centres to assess conditions.