role in the kidnapping of British photojournalist John Cantlie and his Dutch colleague Jeroen Oerlemans.

Cantlie and Oerlemans were held captive for nine days after they strayed into a jihadist camp in northern Syria where Islam was working.

Islam maintains he was simply a medic who was not affiliated to any terror groups, but when he returned to the UK in 2013, he was arrested at Heathrow Airport and held in Sussex Police's specialist counter-terrorism units.

Islam was charged alongside his younger brother Najul Islam, who had worked in the Department for Work and Pensions before travelling to Syria, and Jubayer Chowdhury.

All three were held in the high security Belmarsh Prison until they were charged with terrorism offences to appear in Kingston Crown Court.

At the time, intelligence officials were quoted assaying their questioning would help trace the killer of journalist James Foley, who was beheaded by the Islamic State (Isis).

However, in November 2013, Crown Prosecution Service (CPS) lawyer Mark Dennis announced he was unable to proceed as the witnesses, Cantlie and Oerleman, were unable to attend court.

"A problem arose for the prosecution which serves to frustrate the trial from the point of view of the prosecution," Dennis said, according to a BBC report at the time.

"The two victims in the case are the two prosecution witnesses on which the case rested wholly on their evidence. The prosecution are unable to call either victim for the purposes of the trial listed today."

Cantlie had remained in Syria and was later kidnapped again, becoming the last-known Western journalist to be taken