A former captive of the Islamic State has given a chilling account of how militant Jihadi John would stage mock executions.

"Jihadi John" is the moniker of the militant who would eventually be revealed as Mohammed Emwazi, a 26-year-old West Londoner who features prominently in several of ISIS' execution videos. He first appeared in the execution video of James Foley, and most recently in footage of Kenji Goto's murder.

Javier Espinosa, a correspondent for Spain's El Mundo newspaper and former hostage, said that Emwazi staged the fake executions for "maximum drama." He said that the British jihadi would usually brandish an ancient sword reportedly used by Muslims during the Middle Ages and press it against his neck. He would then taunt Espinosa by telling him how the sword would be used to behead him.

"The first hit will sever your veins. The blood mixes with your saliva," Espinosa quoted his captor in his article at the Sunday Times.

"The second blow opens your neck. You wouldn't be able to breathe through your nose," Jihadi John added.

Espinosa then said that Emwazi would proceed to using the Glock pistol to taunt his hostages, taking it out, pressing it against the hostage's head and pulling the trigger three times. 

The journalist revealed that mock executions were only one form of "psychological and physical torture, privations and humiliations" that marked the daily life for the 23 people in his group.

Mr Espinosa was abducted by the Islamic State in September 2013 in Syria, where he was covering fighting between Syrian rebels and forces under Syrian President Bashar al-Assad's government. He endured six months of captivity at the hands of the militants until he was released in March last year.