They want to come back to Britain but are put off by the threat of jail terms

He and 30 others are said to be unhappy with the course of the conflict

Research institute says it has been contacted by fighter in the region

But it is said some of them are now tired of the conflict and want to return

More than 500 Britons have gone to Syria to fight alongside Islamists

British jihadis fighting in Syria want to come home after becoming disillusioned with the conflict, it emerged today.

In the last three years, more than 500 radicalised Britons are believed to have headed out to the war-torn country, where Islamist groups are fighting President Bashar Assad's forces.

But some of those who signed up to fight have now contacted authorities in Britain saying they have had enough of the war-zone and want to return home, it was reported today.

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An armed ISIS member parades through the streets of Raqqa, Syria, waving a jihadist flag. It is said that some Britons fighting alongside Jihadis in the country now want to return home

A man representing a group of 30 militants reportedly contacted King's College London's International Centre for the Study of Radicalisation and Political Violence (ICSR), telling them his group want to come back.

The men, who went to the region in the hope of toppling President Assad, are reportedly unhappy at having to fight against other rebel factions.

According to The Times, the man told researchers: 'We came to fight the regime and instead we are involved in gang warfare. It's not what we came for but if we go back [to Britain] we will go to jail.'

The ICSR's Professor Peter Neumann told newspaper: 'The people we have been talking to... want to quit but feel trapped because all the Government is talking about is locking them up for 30 years.'

He believes as many as a fifth of British fighters in the country could be trying to find a way out of their current situation.

He claimed less-hardened jihadists could be used to show would-be recruits that the reality of battle may not match the image presented by ISIS propaganda.

At least 40 of the estimated 250 Britons to have already returned from the region have been arrested and are now facing trial on terrorism charges.

An ISIS militant in Syria prepares to set fire to what appears to be a British passport in a recent extremist video

Labour leader Ed Miliband has suggested a mandatory programme of de-radicalisation for people involved on the fringes of radical groups like ISIS.

But the government has been reluctant to support any scheme which could allow wrongdoers to escape punishment for their crimes.

News of waning morale among British jihadis came after terrorism experts said social media posts show many Westerners who took up arms are 'immature'.

After studying what fighters had posted online, Professor Greg Barton, from the Global Terrorism Research Centre at Monash University, told Daily Mail Australia: 'We're dealing with young men doing foolish things, driven by peer pressure and a desire for affirmation.

'I think it's generally true from (their) social media posts that what we see reflects a fairly juvenile mentality.'

Mohammed el-Araj (left) and Abu Hujama al-Britani (right), both from London, died fighting with extremists

Yesterday, a fighter who defected from ISIS said the British militant seen in recent execution videos - who is known as 'Jihadi John' - was chosen to carry out the task to make other Westerners feel 'part of cause'.

The man told CNN: 'It is possible that the goal was to project the image that a European or a Western person executed an American so that they can showcase their Western members and appeal to others outside Syria.'

Led by Abu Bakr al-Baghdadi, ISIS - which comes from the Arabic word 'al-Sham', meaning Levant, Syria or Damascus - has overrun large areas of Syria and Iraq.

In June, it seized control of Mosul, Fallujah and Tikrit in northern Iraq in a series of deadly military offensives.

Although its exact size is unclear, the extremist group is believed to include thousands of fighters and is highly fanatical, often killing Shia Muslims and Christians.

This week, the Islamic State released a video featuring British aid worker David Haines (right), who has been threatened with execution. David Cameron (left) is coming under rising pressure to unleash a military response

This week, the group released a video of U.S. journalist Steven Sotloff being beheaded, calling the execution retaliation for U.S. air strikes.

The footage also featured British aid worker David Haines, 44, who was captured by militants near Atmeh refugee camp in Syria and has been threatened with beheading.

David Cameron, who is coming under growing pressure to unleash a military response, said Britain would use 'everything we have in our armoury' to squeeze ISIS out of existence.

But yesterday, he told fellow Nato leaders not to pay ransoms for hostages as it only increases kidnappings and funds further terrorism.