A jihadi fighter in Syria has told Sky News he has been training British teenagers as young as 16 to fight in the war.

Yilmaz, a Dutch national who has been in the region for two years, said: "It's extremely easy to get here … People go on holiday, they end up in Syria."

Speaking via Skype, from the Idlib province of the war-torn country, the fighter insisted the majority of Britons did not pose a threat to their home country.

But he added: "There is always the chance of a loose cannon doing something stupid, doing something crazy."

Asked how young his trainees from Britain were he replied: "16, 17 ... Most are in their 20s."

Security services in the UK estimate 400 to 500 British jihadists are involved in the conflict in Syria or Iraq, and there are concerns some may wish to return and commit terrorist acts when they return.

Three Muslims from Cardiff have appeared in an ISIS video from Syria and last week a social media account in the name of one of them posted pictures of homemade bombs.

Nasser Muthana, 20, appeared to warn that Britain should be afraid to allow him to return.

But Yilmaz, who was in the Dutch army and also worked in an old people's home in Holland, told Sky News: "We see this jihad in Syria as something holy.

"When I speak to the British fighters and the foreign fighters here, I just can't see them risking everything, coming home and committing crimes.

"It's funny, the British Government itself is funding and training, be it in Jordan or Syria, the Free Syrian Army. So the British Government is helping and I'm helping in my own way."

Yilmaz says he supports the goal of ISIS to overthrow the Syrian regime - but believes Iraq is a distraction.

On Sunday, it emerged that two 16-year-old twin sisters from Manchester had fled to Syria where it is feared they may have joined the ISIS fight.

Giving an insight into women's roles among his fighters, Yilmaz said: "Some brothers brought their wives or their sisters - but it's a supporting role, housework, washing, fixing clothes … there's no need for female fighters."

A British-born Londoner in the UK who converted to Islam six years ago told Sky News he believes it is his duty to go to Syria.

Suliman, who says he has not gone for family reasons, said: "It is the best death. If you are to die out there on the battlefield, it is the best death - if I did die - I'd have done something good for people, and that would surely be written down as a good deed."

Both Suliman and Yilmaz say they were influenced in their views about Syria by YouTube videos and by social media.

Haras Rariq, of the anti-extremist organisation the Quilliam Foundation, said: "The overwhelming majority of Muslims will reject going out to fight ISIS and rightly so, they shouldn't go. It's not Islamic, it's not what the Prophet talked about.

"But the problem is a small number will go and they're the people that we need to worry about."