Shabazz Suleman, 18, left his family in Turkey to go and fight for Isis in Syria.

A British teenager who fled to Syria to fight for Isis now wants to return and face justice.

Shabazz Suleman, 18, disappeared while on a family holiday to Turkey three years ago and had been in Raqqa, the de facto capital of Islamic State, until its recent fall.

The former grammar school pupil from High Wycombe, Buckinghamshire, told The Times that he had become disillusioned with jihadism and chose to desert the terrorist group.

Via encrypted messages he told the newspaper he went through "intense" indoctrination by the group, adding: "I never thought I was being brainwashed until I saw the way they treat other Sunnis."

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Suleman, who is thought to have left IS-controlled territory and be in the hands of a Turkish militia, reportedly admits undergoing weapons training and carrying out guard duties, but denies taking part in killings.

His father, Afzal Suleman, 46, said he knew "for a fact" that his son had become a civilian and had not been on the battlefield for two years.

"(He) never killed anyone or anything," Suleman told the newspaper.

"At the end of the day if he has committed a crime he should go to court. We just want him home."

Suleman's hopes to return emerged after Government minister Rory Stewart said the only way of dealing with British Islamic State fighters in Syria would be to kill them in almost every case.

His remarks came after Max Hill QC, the independent reviewer of terrorism legislation, called for a focus on "reintegration" in cases where authorities have decided individuals who return should not face prosecution.

Hill said it was right that security services have left space for those who travelled out of a sense of naivety, at a young age and who return in a "state of utter disillusionment" to be diverted away from the criminal courts.

A report released this week said Britain has one of the largest populations of returning fighters and others who travelled to join Islamic State.