Young British men and women fighting in Syria is a "huge problem" with an estimated 500 UK citizens joining radicals abroad, Jonathan Russell told Good Morning Britain.
Political liaison officer at the anti-extremism organisation Quilliam Foundation described British men and women going to Somalia or Syria to fight as "the new face of terrorism".
More top news
Former Girls Aloud singer Kimberley Walsh is pregnant with her second child, she has revealed.
Chancellor George Osborne will seek to reassure financial markets on Monday morning following Britain's decision to leave the EU.
In his first outing since the referendum result, the lead Leave campaigner has outlined his vision for a post-Brexit Britain.