At least four Western hostages held by the Islamic State in Syria, including murdered US journalist James Foley, were waterboarded in the early part of their captivity, the The Washington Post reported Thursday.

Waterboarding, which was used by the CIA during interrogations of suspected terrorists after the September 11, 2001, attacks, is a widely condemned form of torture — including most recently by US President Barack Obama — that simulates drowning,

“Waterboarding often involves strapping a person down on a gurney or bench and pouring cold water over a cloth covering the face. It causes the sensation of drowning,” explains the paper.

“They [IS jihadists] knew exactly how it was done,” a person with knowledge of what happened to the hostages told The Washington Post.

American journalist James Foley, kneeling in orange, in a video released by the Islamic State, which apparently showed him being beheaded by his captor, August 19, 2014. (screen capture: YouTube/News of the World)

American journalist James Foley, kneeling in orange, in a video released by the Islamic State, which apparently showed him being beheaded by his captor, August 19, 2014. (screen capture: YouTube/News of the World)

A second person said : “Yes, that is part of the information that bubbled up, and Jim was subject to it. I believe he suffered a lot of physical abuse.”

A French journalist who was kidnapped by IS in 2013 and held captive with Foley said the US journalist was singled out for extra abuse, including mock executions, because pictures of his brother, a US Air Force pilot, were found on his computer.

Foley was purportedly killed last week in a gruesome video posted online, showing his beheading, followed by the appearance of another US journalist, Steven Sotloff, whom the London-accented IS jihadist threatens to kill next should US strikes on the militants in Iraq continue.

London rapper Abdel-Majed Abdel Bary, reportedly a key suspect in the beheading of US journalist James Foley (screen capture: YouTube/BVMUndergroundHipHop)

London rapper Abdel-Majed Abdel Bary, reportedly a key suspect in the beheading of US journalist James Foley (screen capture: YouTube/BVMUndergroundHipHop)

The alleged executioner was said to be identified as a British rapper who joined the Islamic State last year.

Abdel-Majed Abdel Bary, 23, from Maida Vale, London, is a key suspect in the case.

According to witnesses, Foley was seized in the northern Syrian province of Idlib on November 22, 2012. His family had not heard from him since, despite a public campaign for information.

The US described his murder as a terrorist act.