Islamic state Brit
During a 10-minute propaganda video Brit Siddartha Dhar or Abu Rumaysah al-Britani threatened David Cameron and the UKIsis propaganda video

Great Britain could be attacked by 70 "high threat" jihadists who have returned from fighting with Islamic State (Isis), a senior Home Office official has warned. An estimated 350 British jihadists have returned from fighting in the extremist's self-declared caliphate that bridges Syria and Iraq.

German and Italian intelligence chiefs believe that Daesh (Isis) is planning an imminent attack on holidaymakers on European beaches this summer. And according to Scott Wilson, the national co-ordinator of the Protect and Prepare counterterrorism programmes, up to a fifth of the returning jihadis could be planning attacks on UK landmarks.

On 17 April, a Birmingham teenager was arrested at Manchester airport on suspicion of committing "Syria-related terrorism offences" whilst en-route back to the UK. His has since been bailed.

Only the day before five people from Birmingham were apprehended by West Midlands Police in the city and at Gatwick Airport. The five were suspected of having links to terrorists in mainland Europe and were potentially targeting UK landmarks like the London Eye.

Wilson told the Security and Counter Terror Expo in London that Isis had built up a level of support that had eclipsed that of al-Qaeda as he revealed the stunning numbers. "I cannot answer where it is going to go," he said in The Times. "It [the terrorism threat] is going to be with us for a long, long time."

Around 800 British extremists are believed to have joined Isis with counter-extremism programmes such as Prevent available to those on return. But many will have not attended the programme and security chiefs believe that former fighters could well be planning attacks as well as spreading Isis propaganda and recruiting fighters.

The group has threatened the UK and its Prime Minister David Cameron in a number of its slickly-edited propaganda videos. And the terrorists suspected of carrying out the deadly terrorist attacks on Paris and Brussels were European citizens who had travelled to the Middle East for training —with some posing as Syrian refugees to re enter the EU.

At the same Expo officials from both the EU and Nato said they believed isis is trying to obtain nuclear and chemical weapons. But the UK, outside of the Schengen Zone, is a significantly harder target to attack compared to France or Belgium.