London, Jul 24 (IANS): Two British Islamic State (IS) members have finally admitted to holding an American aid worker hostage in Syria, where she was abused and tortured before her death in 2015, a media report said.

Alexanda Kotey and El Shafee Elsheikh, who are both in US military custody in Iraq, had previously denied ever meeting Kayla Mueller, but in interview tapes obtained by NBC News they admitted to their involvement, the Daily Mail newspaper said in the report on Thursday.

"She was in a large room, it was dark, and she was alone, and she was very scared," said Elsheikh, a member of the IS execution squad dubbed the 'Beatles' because of their British accents.

"I took an email from her myself," he said, while referring to a mail id the terror group could use to demand ransom from the family.

Kotey added: "She was in a room by herself that no one would go in."

The IS reportedly demanded 5 million euros from Mueller's family, telling them that that they would send "a picture of Kayla's dead body" if their demands were not met.

Mueller, an international aid worker, was abducted in Syria in 2013.

During her captivity, she was raped by the former IS leader, Abu Bakr al Baghdadi, who killed himself with a suicide vest as American commandos closed in on him in a raid last year, reports Daily Mail.

Kotey and Elsheikh are two of the four so-called IS 'Beatles', a hostage-taking execution squad responsible for beheading numerous Western captives, including Americans James Foley, Steven Sotloff and Peter Kassig.

The other two 'Beatles' are Mohammed Emmwazi, aka 'Jihadi John', who was killed by a CIA drone strike in 2015, and Aine Lesley Davis, who was sentenced to seven and a half years in prison in Turkey in 2017.