UK to continue evacuations despite Kabul attack: Boris Johnson

Britain will continue the operation to evacuate nationals and Afghans from Kabul despite Thursday's "barbaric" bomb attack, Prime Minister Boris Johnson said.

"We've been ready for it," he said of the attack. "We're going to continue with that operation, we're now coming towards the very end of it in any event.

"We're going to work flat out... getting people through as fast as they can still, and we're going to keep going up until the last moment," said the prime minister, shortly after chairing a meeting of the emergency COBR committee.

He said that members of the US military had "very sadly" lost their lives in the attacks, as well as "many Afghan casualties".

The threat of a terrorist attack was "one of the constraints that we've been operating under" during the operation, he added.

Read | 'Total panic' as deadly blasts rock Kabul airport

"But, clearly, what this attack shows is the importance of continuing that work in as fast and as efficient manner as possible in the hours that remain to us, and that's what we're going to do."

The UK leader called the attacks "barbaric", and paid tribute to the "phenomenal effort" of those involved in the evacuation operation.

"There's been nothing like it for decades and decades," he said, adding that the "overwhelming majority of those who are eligible have now been extracted from Afghanistan."

Around 12,000 Britons and Afghans who assisted the country during the war have been evacuated in the operation, said Johnson.

The Ministry of Defence later said on Twitter that "there have been no reported UK military or UK government casualties following the incidents in Kabul.

"UK forces are working closely with our partners to provide security and medical assistance," it added.

Two explosions struck near the main gate of the airport, causing multiple casualties in what the US military labelled a "complex attack" that took place as countries raced to complete evacuations from Afghanistan.

One explosion hit the Baron Hotel, about 200 yards (metres) from the Abbey Gate, which had been used by some western nations as a staging point for evacuations since the airlift began on August 14.

In the wake of the attack, the British government issued a "Notice to Aviation", advising airlines to avoid Afghan airspace under 7,600 metres (25,000 feet).