Senior leaders of an offshoot of al-Qaeda in Syria — the Nusra Front, recently renamed the Fateh al-Sham Front — are believed to be on the ground actively working on attack plans

A resurgent al-Qaeda is plotting attacks against Britain with renewed vigour as Islamic State comes under pressure, sources said last night.

Sir Michael Fallon, the defence secretary, also told The Times that the terrorist network posed a “very direct threat” to the UK and Europe.

An offshoot in Syria — the Nusra Front, recently renamed the Fateh al-Sham Front — is regarded by the West as the most potent, with senior leaders believed to be on the ground actively working on attack plans. One figurehead of the group was reportedly killed in a US drone strike on Monday.

Elements of Osama bin Laden’s core group are also returning to southern Afghanistan 15 years after they were forced to flee by the US-led invasion, while an