- About 15% of UK fanatics who have fled to fight with ISIS have been killed
- Up to 850 British jihadists have joined ISIS and half said to have returned
- Former British military commander Richard Kemp now fears an attack on home soil
One in six British jihadis who have gone to Syria and Iraq to fight with ISIS have been killed - but 400 are back in the UK, it has been claimed.
Security chiefs believe at least 15 per cent of all British extremists who have fled to join the terror group have been wiped out amid intensified airstrikes and military operations on the ground.
But with 850 fanatics believed to have travelled to ISIS strongholds from Britain, there are fresh fears that half of them have already returned.
One in six British jihadis who have gone to Syria and Iraq to fight with ISIS, including Jihadi John (pictured), have been killed - but 400 are back in the UK, it has been claimed
Colonel Richard Kemp, the former commander of British forces in Afghanistan, told Dan Warburton of the Sunday Mirror: 'My concern is more with the 400 or so who have returned to the UK and pose a threat.
We have seen what the Islamic State can do in Brussels, in Paris, in the US and most recently in Turkey.
'They can, and will, try to do the same thing here. I think that’s what is most concerning. We are not actually being effective in killing them in large numbers as we need to be.
'Our failure to wholeheartedly attack Islamic State gives people the inspiration to carry out attacks.'
His comments come days after it emerged that Britain will almost double its number of troops in Iraq
A total of 250 military personnel are to deploy to the war-torn region to help in the fight against ISIS at the end of the summer. They will join around 300 soldiers already there.
Earlier this month it was reported that at least 85 British jihadists fighting in Syria have been killed.
The Defence Secretary Michael Fallon revealed around 850 people linked to the UK and regarded as a security threat are now believed to have taken part in the bloody civil war.
A staggering 50 per cent of those have returned to the UK, raising fears the battle-hardened warriors could be inspired to carry out lone-wolf attacks in Britain.
High-profile British deaths have included Mohammed Emwazi, who became known as Jihadi John after he appeared in barbaric videos in which he murdered UK and US hostages.
The 26-year-old Kuwaiti-born was killed in a drone strike last year.
In September, RAF warplanes killed two British jihadists who were plotting attacks on British soil.
Shadow Foreign Office minister Diana Johnson said the figures highlighted the ‘grim reality’ for those lured to join ISIS.
But she said ministers must do more to explain how the 400 or so ‘homegrown extremists’ are being managed following their return to the UK.
The Government believes the number of foreign fighters joining IS has fallen to around 200 a month from its peak of 2,000.
Meanwhile there are claims an SAS soldier killed three ISIS fighters in Iraq using a Gurkha knife.
According to John Ward of the Daily Star Sunday, the sergeant, was part of a number of SAS advisers helping Iraqi troops during the battle for Fallujah.
He is said to have been caught up in an ambush before using the knife after running out of ammunition in a bid to avoid being captured alive.
It comes after it was reported that SAS troops in Libya have shot dead three British jihadists during a half-hour gun battle.
The men were killed during fighting in Sirte as part of moves to liberate ISIS strongholds in the area.
According to Marco Giannangeli and James Murray of the Sunday Express, the men were aged about 25 and were in enemy vehicles destroyed by the SAS. Documents found at the scene suggested they were from Britain.