(Middle East Eye) -- Prince Miteb bin Abdullah, the son of the late King Abdullah who was once considered a future crown prince, was beaten and tortured, along with five other princes, when he was arrested and interrogated in Riyadh during the ongoing political purge in the kingdom, Middle East Eye has confirmed.

All six princes were admitted to hospital in the 24 hours following their arrest. One of the men was in such a bad condition that he was admitted to the hospital’s intensive care unit - treatment which occurs when there is a high risk to the life of a patient, such as organ failure, from the heart, lungs, kidneys, or high blood pressure.

Hospital staff were told that the injuries sustained in each case were the result of “suicide attempts”. All had been severely beaten, but none of them had fractures. The marks on their bodies were consistent with the imprints left by military boots.

At least 17 of those detained were taken to hospital, but the number maltreated in the purge ordered by the current Crown Prince Mohammed bin Salman is certainly higher, according to sources who MEE is unable to identify because of concerns for their safety.

MEE has learned that medical units have now been installed in the Ritz-Carlton hotel where the beatings have taken place. This is to prevent torture victims from being taken to hospital.

MEE has also learned that in addition to the Ritz-Carlton, the detainees were also held in two other hotels including the Courtyard, Diplomatic Quarter hotel which is across the road from the Ritz-Carlton.

Both the Ritz-Carlton and the Courtyard are run by the Marriott International hotel chain. A spokesperson for Marriott International told MEE on Friday that the Ritz-Carlton and the Courtyard, Diplomatic Quarter were “not operating as traditional hotels for the time being”.

According to a civil rights attorney in Houston, Texas, the hotels are only liable to Saudi Arabian laws.

"If there is a crime being committed, then that crime is governed by the country which you are in," Randall Kallinen told MEE.

Both hotels appeared to be booked out and not admitting guests for the whole of December, according to their websites on Friday.

Prince Miteb, who is 65, served as minister of the National Guard, a military force drawn from tribes loyal to the House of Saud whose main role is to protect the royal family, from 2013 until his arrest on 4 November.

Prince Miteb has a background in the military and was considered among the possible contenders to inherit his father's throne prior to the appointment of the current King Salman as crown prince in 2012.

MEE can also confirm that Prince Abdul Aziz bin Fahd, the son of the late King Fahd who was arrested after this year’s Hajj in early September, was admitted to hospital close to the time of his arrest, although his fate is still unclear.

Courtyard by Marriott Riyadh Diplomatic Quarter (Marriott)

The purge, conducted in the name of an anti-corruption drive, has also involved the freezing of around 1,700 bank accounts.

According to one US source, bin Salman has claimed he intends to collect $1 trillion from the princes and businessmen that he has arrested.

The Financial Times newspaper reported on Thursday that Saudi authorities were offering deals to detainees, including billionaire tycoons such as Al-Waleed bin Talal bin Abdulaziz, in which they would surrender up to 70 percent of their wealth in return for their freedom.

The arrests, interrogation and mistreatment being conducted in hotels owned by a US-based chain with an international reputation has raised questions about how Marriott International has allowed its facilities to be used in such a way.

MEE asked Marriott International to clarify what its company policy was on allowing its premises to be used as detention facilities and asked for comment on allegations that detainees were being tortured.

A spokesperson said: "The Ritz-Carlton, Riyadh and the Courtyard, Diplomatic Quarter are not operating as traditional hotels for the time being. We continue to work with the local authorities on this matter.

"We remain in close contact with the guests and groups holding existing reservations; working with them to assist with their reservations and minimise disruption to their travel and event plans."

(Photo: Prince Miteb bin Abdullah, pictured in Paris in 2014, Reuters)