Mokhtar Belmokhtar, an extremist linked to al-Qaeda, on Sunday released a video taking responsibility for the “blessed operation”, which he said was a response to the French military intervention in Mali, which borders Algeria to the south.

Speaking at Chequers on Sunday, Mr Cameron acknowledged that the terrorist threat in North Africa had grown and he predicted a prolonged struggle to meet it.

“It will require a response that is about years, even decades, rather than months and it requires a response that is patient, that is painstaking, that is tough but also intelligent, but above all has an absolutely iron resolve; and that is what we will deliver over these coming years,” he said.

William Hague, the Foreign Secretary, signalled that could mean directing more of Britain’s growing aid budget to countries in the region.