LONDON: Prime Minister Boris Johnson on Friday promised Britain's full support for Afghanistan, to stop it becoming a haven for extremists, as cities fall to the Taliban after the withdrawal of Western forces.

"What we must do now is not turn our backs on Afghanistan but continue, as a member of the (UN) Security Council, a country deeply involved in the strategic future of the area, to work with our partners, and make sure the government of Kabul does not allow that country, again, to be a breeding ground for terror," he said.