Russian Foreign Ministry has expressed indignation at another case of vandalism of the Soviet Army monument in Bulgaria's capital city of Sofia.

The Bulgarian Ministry of Foreign Affairs has been given a letter of protest demanding "a thorough investigation of the vandal incident, indicting the perpetrators and taking the necessary measures to maintain the monument presentable," ITAR-TASS news agency reports.

On the night of 22 February the Soviet Army monument in Sofia was painted in solidarity with Ukraine.

A Ukrainian flag was drawn on the front fa?ade of the monument, with the message "Glory to Ukraine" written underneath in Ukrainian. Obscene words in reference to the Russian President Vladimir Putin were also written in graffiti.

This is the 3rd time the monument has been painted by unknown perpetrators. On a previous occasion, the act stirred outrage from the Russian Embassy in Sofia.