Bulgaria's foreign ministry on Friday announced the expulsion of 10 Russian diplomats for breaching international conventions on diplomatic ties.

The wording used by the ministry is often a reference to espionage. Sofia expelled two Russian diplomats earlier this month for similar reasons.

The EU and NATO member has strong economic ties with Russia but several alleged cases of espionage have hurt links since October 2019.

The latest expulsions come as relations between the West and Moscow hit a new low over Russia's invasion of Ukraine, which has spawned unprecedented sanctions and seen Moscow diplomatically isolated.