Terror group ISIS have released a video showing children as young as ten at a training camp for "junior jihadi's."

The video shows the youngsters brandishing military weapons and firing machine guns while masked in balaclavas.

Children look on as a small child struggles to control an automatic weapon, as he fires it.

Another boy is seen expertly assembling a weapon, while children watch in the background.

It also shows the young children taking an oath pledging an allegiance to the Islamic State.

A small child is asked on camera what he would like to say to infidels.

He replies: "Infidels... you are to be killed."

ISIS Video

It is thought the video is aimed at recruiting more children and young people to the militant group, who in recent months have taken over swathes of territory in Syria and Iraq as their murderous onslaught continues.

A boy, who managed to flee from one of the training camps, told CNN how ISIS tried to recruit him when he was 13 issuing threats to behead his father if he attempted to intervene.

The boy revealed he was forced to attend the camp, where he joined other children for exercise, studied about the Quran and took courses on weapons. He revealed that the children were often forced to watch gruesome videos of beheadings and torture.

"When we go to the mosque, they order us to come the next day at a specific time and place to [watch] heads cut off, lashings or stonings.

"We saw a young man who did not fast for Ramadan, so they crucified him for three days, and we saw a woman being stoned [to death] because she committed adultery."

ISIS Video

The boy managed to escape the camp after his father pulled him out. He and his family then fled to safety in Turkey.

The Islamic State also released a decapitation video yesterday in which they threatened America with more beheadings of hostages.

Just hours earlier Islamic State had released shocking footage of the mass execution of 300 Syrian national army soldiers in the Syrian Desert titled '2ndAmessagetoAmerica.'

The group's first warning ten days ago was entitled 'A Message to America' and showed the decapitation of American journalist James Foley.

ISIS video

The video comes after David Cameron announced yesterday that more armed police will patrol Britain's streets to counter the threat posed by fanatics returning from Iraq and Syria.

He warned that the return of hundreds of extremists from Iraq to the UK, posed a greater threat to British security than Al Qaeda or the IRA ever did.

His comments came as Theresa May announced the official terror threat level had been raised to 'severe' – the second-highest state – for the first time in three years.