Islamic State militants have imposed a new law threatening to jail any man caught wearing skinny jeans or having music on their mobile phones in an apparent crackdown on hipsters.

The terror group said it would also imprison anyone caught smoking or turning up late for prayer in further draconian crackdowns in its Syrian stronghold of Raqqa.

Violators will be jailed for ten days, during which time they will be made to take an 'Islamic course', it was reported by anti-ISIS informants in the city.

At the end of their prison term, they will be forced to take a test, with those who pass being released immediately. Those who don't will be fined and kept in prison until they pass.

Outlawed: Militants fighting for the Islamic State (left) have threatened to jail anyone caught wearing skinny jeans (like the ones pictured, right) in its latest draconian crackdown in the Syrian stronghold of Raqqa

The introduction of the new laws were revealed by the anti-ISIS campaign group Raqqa is Being Slaughtered Silently (RBSS) who risk their lives leaking information from inside the city.

RBSS says the sanctions are 'volatile and changeable' but notes that they are becoming increasingly more stringent.

One resident, named only as Jassem, told the group how dozens of people had fled the city in the wake of the jihadi network's brutal enforcement of its twisted form of sharia law.

He said: 'ISIS tightens penalties and uses the principle of intimidation in dealing with public, which led to the migration and escape of many people.

'Freedom of expression has become a crime, so you can not oppose a decision issued by the group.

'Otherwise you will be arrested on charges of violation of God’s law as its fighters claim, but they are far from this law.

'There is no difference between ISIS and Assad’s regime: bribery and favoritism are widespread within the group and play a major role, especially among the local members of the group.'

Up in smoke: Photographs taken in the northern town of Barqah, close to the border with Turkey, show members of ISIS' feared religious police force setting light to vast piles of cigarettes in a field

Shocking: The cigarette burning images emerged as it was revealed ISIS has erected shocking anti-smoking posters throughout its self-declared caliphate featuring images of burning human lungs

Earlier this month, ISIS militants carried out a second mass cigarette burning as the terror group stepped up its anti-smoking campaign.

Photographs taken in the northern town of Barqah, close to the border with Turkey, show members of the group's feared religious police force setting light to vast piles of cigarettes in a field.

The images emerged as it was revealed ISIS has erected shocking anti-smoking posters throughout its self-declared caliphate featuring images of burning human lungs, in the hope it will convince militants to reject the 'slow suicide' caused by cigarettes.

Images also emerged earlier this week showing dozens of black balaclava-wearing extremists graduating from an Islamic State-run school of terror in Raqqa.

School of terror: A senior militant is seen giving the jihadi graduates a final lecture before they are sent off to wage jihad in the various provinces - known as wilayats - under the control of the Islamic State

Militants: Brandishing AK47 assault rifles and waving flags carrying the sinister black and white ISIS logo, the photographs showing the jihadi 'Class of 2015' are believed to have been taken in Raqqa city

Brandishing AK47 assault rifles and waving flags carrying the sinister black and white ISIS logo, the photographs showing the jihadi 'Class of 2015' are believed to have been taken in Raqqa city.

Although the are dressed in head-to-toe black and wear balaclavas that cover most of their faces, it is clear that the majority of the graduates are teenagers who have been brainwashed into thinking they are holy warriors, when the reality is they will be little more than cannon fodder.

The images are believed to have been taken somewhere in the city of Raqqa - the eponymous capital of the province and a stronghold of the terrorists' self-declared caliphate, which covers vast swathes of land in northern Syria and western Iraq.

The photographs show dozens of militants sitting on seats in what appears to be a school hall, while chilling black and banners carrying the ISIS logo are seen been waved.

A senior militant is seen giving the jihadi graduates a final lecture before they are sent off to wage jihad in the various provinces - known as wilayats - under the control of the Islamic State.

Having been given a final speech by their commanders, the fighters are seen waving ISIS flags in celebration before taking part in what appears to be a passing out parade.