Amnesty International has said it has credible and "extremely alarming" evidence that post-coup detainees in Turkey are being beaten and tortured, including by rape, the use of stress positions and starvation.

The human rights organisation demanded that independent monitors be given immediate access to detainees being held in police headquarters, sports centres and court-houses by authorities under President Recep Tayyip Erdogan.

More than 10,000 people have been detained since the failed coup of July 15, according to Amnesty.

Having spoken to lawyers, doctors and a person on duty in a detention facility about the conditions detainees were being held in, Amnesty said: "The organization heard multiple reports of detainees being held in unofficial locations such as sports centres and a stable. Some detainees, including at least three judges, were held in the corridors of courthouses."

The organisation said it heard "extremely alarming accounts of torture and other ill-treatment of detainees, particularly at the Ankara Police Headquarters sports hall, Ankara Başkent sports hall and the riding club stables there". It went on: "According to these accounts, police held detainees in stress positions, denied them food, water and medical treatment, verbally abused and threatened them and subjected them to beatings and torture, including rape and sexual assault."

Amnesty added that two lawyers in Ankara working on behalf of detainees told the organisation that detainees said they witnessed senior military officers in detention being raped.

Separately, a person on duty at the Ankara Police Headquarters sports hall saw a detainee with "severe wounds consistent with having been beaten, including a large swelling on his head". Amnesty's statement went on: "The detainee could not stand up or focus his eyes and he eventually lost consciousness. While in some cases detainees were afforded limited medical assistance, police refused to allow this detainee essential medical treatment despite his severe injuries. The interviewee heard one police doctor on duty say: 'Let him die. We will say he came to us dead.'"

Amnesty International's Europe director John Dalhuisen said: "Reports of abuse including beatings and rape in detention are extremely alarming, especially given the scale of detentions that we have seen in the past week. The grim details that we have documented are just a snapshot of the abuses that might be happening in places of detention. It is absolutely imperative that the Turkish authorities halt these abhorrent practices and allow international monitors to visit all these detainees in the places they are being held."