Grammar school-educated British jihadist Shabazz Suleman claims Turkish police fed him Domino's pizza in jail before handing him over to ISIS in a prisoner exchange which led to a diplomatic storm

A grammar school-educated British jihadist has claimed Turkish police fed him Domino's pizza in jail before handing him over to ISIS in a prisoner exchange which led to a diplomatic storm.

Shabazz Suleman, 19, a former pupil at the Royal Grammar School in High Wycombe, was among as many as 180 fighters handed back to Islamic State by Turkey in return for the release of diplomats.

The swap, involving 46 Turkish citizens and three local Iraqi staff who were captured when IS stormed the Iraqi city of Mosul in June, has sparked a diplomatic row, with Turkey already under pressure from fellow UN members to secure its borders with Syria.

Speaking for the first time since the deal in September, Suleman has claimed he and fellow captives were able to contact ISIS from internet in their cells, and that the Turkish police guarding him had expressed sympathy with their cause - and even bought them pizza.

'Cops were very friendly,' Suleman told The Times' John Simpson and Alex Christie-Miller via an online exchange from ISIS stronghold Raqqa. 'Understood why we wanted to fight in Syria. They hated Assad, Israel etc. Their ideology was that of the Muslim brotherhood.

'It was good lol. Had pizza in prison. Dominos lol. Was allowed net. We spoke to dawla [ISIS] in prison. Watched ISIS videos. Sang nasheeds [Islamic chants].'

Suleman, who now calls himself Abu Shamil Al-Muslim, is thought to have joined jihadis in Syria after giving his parents the slip to cross the border while on holiday in Turkey.

The teenager, who was described by his old school as 'a valued, hardworking student', had achieved good A-level results last summer and had a place lined up to study at Keele University, where he had wanted to study International Relations.

Former pupils at his old school include Secretary of State for Justice Chris Grayling, comedian Jimmy Carr, England rugby players Nick Beale, Matt Dawson, and Tom Rees, golfer Luke Donald and singer Ian Dury.

In a statement released in October, after news emerged that Suleman had gone to Syria, the school said: 'During his time at RGS, Shabazz was a very engaging and amiable student who fitted in well, forming good relationships with his peers and staff. Shabazz had a good work ethic, and was prepared to play a prominent role in class discussions, even though he gave the impression of being a rather reserved and quiet person.

Suleman (pictured) claims he and fellow captives were able to contact ISIS from internet in their cells, and that the Turkish police guarding him had expressed sympathy with their cause - and even bought them pizza

'He showed real determination to achieve good academic results, working hard to build on his AS grades to achieve a solid set of A levels in History, Economics and Psychology and so gained a place at University. Shabazz was a valued, hardworking student who achieved well and respected the school’s academic and pastoral ethos.'

But Suleman, who had travelled to Aleppo, Syria with an aid convoy in 2013, is believed to have been radicalised by jihadis he met on Twitter.

He is also thought to have attended the Muslim Education Centre in High Wycombe, where one of the British men convicted in the 2006 transatlantic liquid bomb plot also attended. It is around the corner from the teenager’s £400,000 detached family home.

Suleman's mother had previously denied claims he has travelled to the Middle East for violent reasons, telling the press: 'He has gone to do aid work there'.

The Muslim Education Centre has said it was shocked by Suleman’s departure and has condemned the activities of ISIS.

His parents had reported him missing to both British police and the Turkish authorities, and the Foreign and Commonwealth Office had also reported him missing.

Suleman, who received weapons training at a two-week Sharia training camp, said he had been caught by security services at the Syrian border. He said he was visited twice by Turkish intelligence agency MIT, fined, and told he was going to be deported.

The teenager, described by Royal Grammar School, High Wycombe (pictured) as 'a valued, hardworking student', had achieved good A-level results last summer and had a place lined up to study at Keele University

He said he was held along with 35 other ISIS fighters at an 'open' prison in Sanliurfa, around an hour from the Turkish-Syrian border.

Suleman, who is now in Raqqa where his duties involve being on sentry guard, said he had been given the choice of being deported, or being part of the ISIS exchange.

He wrote: 'After a month of waiting they told us buses are waiting outside for u. MIT ran the exchange. Told us we are free. Exchanged at border, We drove into dawla.'

Three French citizens, two Swedes, two Macedonians, one Swiss, and one Belgian are also believed to have been part of the exchange, as well as another Briton, Hisham Folkard, 26.