The fall of Afghanistan to the Taliban is likely to have "emboldened" UK terrorists, the head of MI5 has warned.

Director general Ken McCallum told the BBC that while the terror threat would not change overnight, there could be a "morale boost" for extremists.

And there is also a concern terrorists could regroup and plan "well-developed, sophisticated plots", he said.

A total of 31 late-stage attack plots have been foiled in the UK in the past four years, said Mr. McCallum.

That includes six during the pandemic period alone, he added. While they were largely Islamic extremist plots, there were also a "growing number" of attacks planned by extreme right-wing terrorists.