“It was with great sadness that I learned that two Britons and the child of another British citizen were killed in yesterday's attack,” said Raab.
As the minister specified, two more Britons were injured.
He stressed that terrorists "will never succeed in intimidating" Britain.
The death toll from two explosions at an airport in the Afghan capital rose to 170.
Dmitry Peskov, a spokesman for the Russian leader, said that Russia condemns the bombings in Kabul in the strongest possible terms.