LONDON (AP) — The government of Belarus said Monday that it summoned a British diplomat in protest after its embassy in London was “attacked” and a diplomat injured.

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 said officers were called Sunday evening to a reported disturbance outside the embassy, where “a member of staff reported he had been assaulted and was left with a facial injury.” One man was arrested, police said, and enquiries are continuing.

Belarus’ authoritarian president, Alexander Lukashenko, has unleashed a sweeping crackdown on protesters, journalists and civil society groups since he was reelected in an August 2020 presidential election that the opposition and the West rejected as rigged.