Isis “aims to attack the UK next,” an intelligence report has warned.
The unnamed official, speaking to CNN, claimed following the Paris attacks counter-terrorism authorities believe Isis will attempt to hit Britain.
They claimed British Isis fighters have been told to return home and carry out an attack by senior leaders of the extremist organisation, also known as the Islamic State or Daesh.
Details around the alleged threat are unclear, but the official claimed authorities’ concerns were heightened by MPs decision on Wednesday night to extend air strikes over Syria.
The controversial vote was won by 174 votes, with Britain launching the first round of strikes against Isis within hours of securing the Commons approval.
Tornado jets struck six targets in the Omar oil fields, around 35 miles east of Raqqa – Isis’ self-titled capital. Defence Sectary Michael Fallon said the first strike, aiming to dent the extremists ability to sell oil, was “extremely important”.
Meanwhile, authorities have also sought to limit fears of civilian casualties.
“In the hundreds of air strikes that the RAF has carried out in Iraq, we have had absolutely no civilian casualties reported,” Group Captain Richard Davies, Tornado pilot and station commander at RAF Marham, said in a statement.
“The rules of engagement that our crews apply both in the air and by commanders on the ground mean that I am absolutely confident that that will continue to be the case with operations in Syria.”