A young man from Oxford who became known as 'Jihadi Jack' after he travelled to Syria has not been heard from since July and has been tortured by anti-IS forces, his parents claim.

Jack Letts has not made contact with his parents since July this year after he was taken prisoner by Kurdish militia during his escape from the former Isil stronghold of Raqqa.

The 21-year-old Muslim convert has ceased contact with his parents after last telling them he was intending to carry out a "protest". In the same audio message he said the act "might get him shot".

His middle-class parents have revealed a series of texts and audio messages which detail his experience after being captured by Kurdish forces, the Mail on Sunday reported.

John and Sally Letts, who undertook a week-long hunger strike to highlight their son's situation, say he was forced to endure long periods of solitary confinement, starved of food and tortured.