Prisoners held at an Israeli detention camp in the Negev desert are being subjected to widespread physical and mental abuses, with at least one reported case of a man having his limb amputated as a result of injuries sustained from constant handcuffing, according to two whistleblowers who worked at the site.

The sources described harrowing treatment of detainees at the Israeli Sde Teiman camp, which holds Palestinians from Gaza and suspected Hamas militants, including inmates regularly being kept shackled to hospital beds, blindfolded and forced to wear nappies.

According to the two sources, the facility, located approximately 18 miles from the Gaza border, consists of two distinct sections: an enclosure where up to 200 Palestinian detainees from Gaza are confined under severe physical restrictions inside cages, and a field hospital where dozens of patients with war injuries are handcuffed to their beds and often deprived of pain relief.

One whistleblower, who has worked in the facility as a prison guard, said detainees were forced to stand up for hours, or to sit on their knees. The source, who spoke out at risk of reprisals, said several detainees were beaten with truncheons and not able to move their heads or to speak at the facility.

“The prisoners are detained in a sort of cages, all blindfolded and handcuffed,” the source said. “If someone speaks or moves, they are immediately silenced or they are forced to stand with their hands raised above their head and handcuffed for up to one hour.

“If they are unable to keep their hands raised, the soldiers attach the handcuffs to the bars of the cage. Many of the detainees had infected wounds that were not being properly treated.”

He added: “The floor is very dirty, and it smells so bad that we were forced to wear face masks. You could hear sometimes the sound of beating and them screaming, and [a] banging sound like against the metal wall.”

The whistleblower said prisoners were given one cucumber, a few slices of bread and a cup of cheese, and that some of them were visibly malnourished.

The source claimed the military had no proof that detainees were all members of Hamas, with some inmates repeatedly asking why they were there. According to the whistleblower, most were considered suspects and some were released. “But they had not been formally charged. It was a kind of filtering camp, a provisional detention,” he said.

According to a report by Physicians for Human Rights (PHR), which demanded the closure of the camp, “since the start of the war, all Gazan residents detained are classified as ‘unlawful combatants’, a classification which deprives them of prisoner of war status, enabling Israel to prohibit lawyers’ visits for prolonged periods, leading to a lack of critical oversight during a time of heightened risk of severe incarceration conditions and torture.”

According to information obtained from the Israeli prison service dating from early April, 849 individuals classified as “unlawful combatants” were being held in its custody.

The source described the field hospital in the detention camp as consisting of tents with an emergency room where patients underwent surgery on a stretcher as there was no operating table. The patients were handcuffed to the beds, they all had nappies and were blindfolded.

He claimed he was told that some patients had come from hospitals in Gaza. “These were patients who had been captured by the Israeli army while being treated in Gaza hospitals and brought here. They had limbs and infected wounds. They were moaning in pain.”

In one case, he said, he learned that a detainee’s hand had been amputated “because the wrists had become gangrenous due to handcuffing wounds.”

The PHR report detailed the case of Izz ad-Din al-Bana, a 34-year-old Gaza resident who relied on a wheelchair before his arrest, and who died at another medical centre in February after being transferred from Sde Teiman to be treated for severe pressure ulcers. Other prisoners alleged that he had been complaining of pain for several days and did not receive an appropriate response or treatment.

The prison guard’s statements are corroborated by a second whistleblower who spoke to the Guardian and who was part of the medical staff operating in the field hospital in Sde Teiman.

“There were about 15 patients in total, they were all handcuffed and blindfolded,” he said. “They were naked, wearing diapers and were covered by blankets. Most of them appeared to have obvious war injuries, some had undergone amputations and others underwent major abdominal or chest surgery. They were practically naked except for a diaper.”

The member of the medical staff added: “I understand that it is difficult to treat a patient accused of heinous crimes, but it is the job we have chosen and as physicians we should recognise that every human being has a right to appropriate healthcare regardless of their backgrounds.”

The source said he witnessed a patient undergoing painful medical procedures without any painkillers.

Responding to the claims, the Israel Defense Forces said in a statement: “Among the detainees held at the Sde Teiman facility are skilled military operatives at a very high level of danger. Detainees are handcuffed according to their level of risk and their state of health.

“Routinely procedures are carried out on handcuffing in order to make sure that the handcuffing is carried in a manner that does not harm the detainees … Early in the war and after reports of handcuff injuries, the type of handcuffs in the facility was changed to reduce, as much as possible, possible harm as a result of the handcuffs.”

It added that detainees were allowed regular access to toilets located in the prison complex and that nappies were used only for those who had undergone medical procedures for which their movement was limited, and were intended to maintain their hygiene.

The IDF said it treated detainees “appropriately and carefully” and “any allegation regarding misconduct by IDF soldiers is examined and dealt with accordingly. In appropriate cases, criminal investigations are opened by the military police.”