Two British nationals and the child of a third British national were killed in Thursday's attack at Kabul airport, British foreign minister Dominic Raab said on Friday.
"These were innocent people and it is a tragedy that as they sought to bring their loved ones to safety in the UK they were murdered by cowardly terrorists," Raab said in a statement.
The Kabul airport attack on Thursday, which killed 13 U.S. troops and at least 79 Afghans, was claimed by Islamic State militants. The Islamic State's Afghan affiliate, ISIS-Khorosan, has emerged as an enemy of both the West and of the Taliban.
Two further British nationals were injured in the attack, Raab added.
"Yesterday's despicable attack underlines the dangers facing those in Afghanistan and reinforces why we are doing all we can to get people out," he said.
Defence minister Ben Wallace said earlier on Friday that Britain would not accept any more people for flights out of Kabul beyond those already inside the airport.
Wallace said Britain was preparing the last 1,000 people inside the airfield who would fly out on Friday as it winds down its 20-year presence in Afghanistan.