New pictures have revealed the inside of a Syrian prison camp where thousands of jihadist fighters who went to join ISIS now spend their days in filthy captivity after the murderous 'caliphate' crumbled to nothing.

ISIS fighters in orange prison jumpsuits are packed into jail cells, many of them lying on the floor of a cramped medical wing at the camp in northern Syria.

There are 5,000 prisoners in the camp, many of them foreign extremists including Britons who are demanding to return to their home countries after their terror group lost its last patch of territory earlier this year.

There are fears that ISIS supporters will stage a raid on prison camps and according to ITV News, which filmed inside the camp, there are also simmering tensions between the extremists who are housed there.

ISIS prisoners in orange jumpsuits lie on the floor of a prison camp in northern Syria where thousands of the jihadists are kept after the 'caliphate' crumbled to nothing

A security guard watches the inmates on a series of screens at the camp in northern Syria amid fears of a raid after ISIS leader Abu Bakr Al-Baghdadi urged his followers to break them out

Elusive ISIS leader Abu Bakr Al-Baghdadi has urged his supporters to break captive ISIS fighters out of prisons, sparking further security fears.

A report by the Institute for the Study of War warned that ISIS wants to 'free its loyal fighters' and is using displacement camps to organize and raise funds.

As a result, there are cameras installed in the prison camp which show several of the cramped jail cells where the ISIS fighters are housed.

According to The Times, which also visited the camp, prisoners are not segregated meaning that boys as young as 12 are kept with some of the most radical inmates.

In Syria, the centres are controlled by the U.S.-backed Syrian Democratic Forces, which spearheaded the fight against ISIS in eastern Syria.

They also do not have the resources to put ISIS fighters on trial, as many of the inmates are demanding.

Tens of thousands of fighters and other members of the group are held in the detention centres across northern Syria and in Iraq.

One prisoner at the camp is Aseel Muthana, who left Cardiff to join ISIS in Syria five years ago at the age of 17.

He travelled to the Middle East shortly after his brother Nasser and another friend had gone to join the terror group.

Inmates at the camp are seen through a grille, including 12-year-old Anas Mohammed (in the blue headband, right). There is no segregation of youngsters and hardened extremists

Another ISIS suspect looks out through a door with another group of inmates in orange jumpsuits sitting behind him. There are numerous such camps in Syria

A large group of inmates is seen in security footage. Experts have warned that ISIS wants to 'free its loyal fighters' and is using displacement camps to organize and raise funds

A masked man stands by the door of one of the cells in northern Syria. Inmates at the camp include British former ice cream seller Aseel Muthana

His family feared he had died but Muthana has now resurfaced at the prison camp in northern Syria and his mother has backed his plea to come home.

'Back then when I first came to ISIS, you have to understand I came way before the caliphate was pronounced,' he said.

'Before all of these beheading videos, before all of the burnings happened, before any of that stuff.

'We came when ISIS propaganda and ISIS media was all about helping the poor, helping the Syrian people.'

The wave of widely publicised ISIS beheadings began later in 2014, when journalist James Foley and British aid worker David Haines were among numerous people murdered in propaganda videos broadcast by the terror group.

However, ISIS had its roots in extremist groups which had been using beheadings during the war in Iraq well before that.

Inmates at one of the centres which are are controlled by the U.S.-backed Syrian Democratic Forces, which spearheaded the fight against ISIS in eastern Syria

Tens of thousands of fighters and other members of the group are held in the detention centres across northern Syria and in Iraq

There are 5,000 prisoners in the camp, many of them foreign extremists who are demanding to return to their home countries

Begging to come home, Muthana said he missed his mother Umm Amin and his former life in the Welsh capital where he worked selling ice cream.

The fate of his brother Nasser remains unclear while his friend Reeyad Khan was killed by a drone strike in 2015.

'Muthana is the latest British ISIS fighter to plea for mercy after the terror group's so-called 'caliphate' crumbled to nothing earlier this year.

Jihadi bride Shamima Begum last week renewed her plea to return, saying her only role in the so-called caliphate was to 'make babies'.

The Government has repeatedly refused her request and then-Home Secretary Sajid Javid stripped her of British citizenship earlier this year.

Another ISIS bride, Tooba Gondal, pleaded to come home with her children in an interview published at the weekend.

'I want to face justice in a British court. I wish to redeem myself. I would like Britain to accept my apology and to give me another chance,' she said.