A group of disillusioned British jihadists who wanted to return home after fighting for Islamic State in Iraq and Syria have been taken prisoner by their militant commanders.

The men were stripped of their weapons and marched to a punishment centre in the militant-held city of Raqqa in Syria, according to reports.

The five Britons were accompanied by three Frenchmen, two Germans and two Belgians. They had complained that they were spending their time fighting other rebel forces instead of the government of Bashar al-Assad and were concerned that they were killing fellow Muslims.

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Five British jihadists who wanted to return home after fighting for Islamic State have been taken prisoners

The men were rounded up after apparently delaying returning to Britain for fear that they would be arrested on arrival.

But security sources say the new development shows that defectors cannot afford to try to bargain with British authorities and should just ‘drop their weapons and leave’.

Until now, IS is thought to have operated an open door policy which has allowed around 250 Britons to return but the start of US air attacks has made militant commanders paranoid that spies could direct attacks.

It means that the formerly welcoming atmosphere for Western militants has now changed to suspicion as the terrorist group begins to turn on its own fighters, according to one security source.

The map shows the control that the extremist Islamic group has gained in Syria and Iraq

The source said the round-up of Westerners is a new development and it is ‘impossible to predict the outcome’. Haras Rafiq, of the counter-extremism think-tank Quilliam, whose members include former fighters, said: ‘It is very dangerous to expose your identity if you want to come back in case IS find out who you are. Anyone who wants to leave, should just leave.’

He said the authorities should still arrest those who have committed crimes abroad, but there also needed to be an option to help reintegrate any who are able to demonstrate that they have ‘genuinely changed’.

It comes after a group of four Britons nick-named ‘the Beatles’ are thought to have become so integrated with IS that one appeared in videos beheading US hostages James Foley and Steven Sotloff.

IS has spent much of its time carving out a caliphate straddling the border of Syria and Iraq, rather than fighting Assad’s forces.

More than 500 Britons have travelled over to join the guerrilla group and around half are thought to have returned, 40 of whom were arrested.

About 20 Britons are believed to have been killed in the civil war in Syria.