The Belarus Foreign Ministry said in a statement that a group of people smeared the facade of the embassy building and then physically assaulted Belarusian diplomats who arrived at the scene.

It added that one of the diplomats “sustained serious injuries requiring urgent medical assistance” and was diagnosed with a broken nose, a concussion and a broken tooth.

The government said it had summoned a British envoy in Minsk to make a formal protest and demand that those responsible be brought to justice.

Posts on social media show a small demonstration outside the Belarusian Embassy on Sunday. London's Metropolitan Police force had no immediate information on the alleged incident.