British intelligence services reportedly tried to recruit the suspected 'New Jihadi John' as a double agent before he managed to flee to Syria, it has emerged.

MI5 approached Siddartha Dhar, also known as Abu Rumaysah, twice to act as an informant.

MI5 officials warned the 32-year-old former bouncy castle salesman that he was likely to end up in jail or dead unless he agreed to become a double agent gathering intelligence on terrorist suspects for the security service.

However the fanatic rejected the approaches and was later arrested on suspicion of being a member of the banned al-Muhajiroun group, the Sunday Times reported.

While on police bail, left Britain with his wife and family for a new life as a jihadist in Syria. He had been arrested six times.

As questions mount over how he managed to flee, pressure built on Sunday 10 January on the police and the Home Office regarding how well the UK's borders are policed.

Lord Carlile, the former independent reviewer of terrorism legislation, told the Press Association that the Home Office should now either release all the relevant documentation or appoint an independent person to review the circumstances of Dhar's flight from the UK and report to the Home Secretary.

"As I commented at the time of Dhar's departure from the UK, the circumstances were a matter of real concern.

"Why had he been granted police bail? Was the CPS consulted? Is there sufficient scrutiny of buses leaving the UK through ferry ports?" Lord Carlile said.

Ruaysah, a former bouncy castle salesman was told that he would most likely be imprisoned or die, according to the Sunday Times.