SOFIA: Bulgaria said on Monday that two Russian diplomats were being expelled from the country, days after the latest in a string of Moscow-linked spy scandals was uncovered. Prosecutors announced on Friday that six people had been arrested on suspicion of spying for Russia, including several defence ministry officials in the EU and NATO member state.

On Monday, they said that “preliminary investigations have shown that two Russian nationals carried out intelligence activity incompatible with diplomatic relations”.

The foreign ministry said that two Russian diplomats had been “declared persona non grata and given 72 hours to leave the country”.

Prosecutors allege that those arrested last week belonged to a spy ring led by an ex-intelligence officer whose wife played the role of intermediary with the Russian embassy.

The Russian embassy warned in a statement on Facebook that it could respond to the expulsions.

It expressed “regret that once again this unfounded action by the Bulgarian authorities will not contribute to constructive dialogue between Russia and Bulgaria”.

“Russia reserves the right to take retaliatory measures,” it said.

The officials arrested last week are accused of passing classified information to the head of the alleged spy ring.