SOFIA, Bulgaria (AP) — Two Russian diplomats accused of spying by Bulgarian prosecutors will be declared persona non grata and expelled from the country, Bulgaria's foreign minister said Friday.

Foreign Minister Ekaterina Zaharieva said that her office had received the letters from the prosecutors with the allegations, and that the Russian ambassador to Sofia would be summoned.

The prosecutor’s office said Friday in a statement that the Russians were engaged in espionage but could not be charged because of their diplomatic immunity.

The diplomats have allegedly collected information about Bulgaria's national elections and energy security, according to prosecutors.

The announcement comes three months after Bulgaria expelled a Russian diplomat identified by prosecutors as being involved in espionage, and also declined a visa to the incoming defense attache at the Russian embassy in Sofia.

In a retaliatory move, Moscow expelled a Bulgarian diplomat a month later.

Bulgaria, Moscow’s closest ally during the Cold War, is a member of NATO and the European Union but is still struggling to reduce its almost total dependence on Russian energy supplies.