SOFIA, Bulgaria (AP) — A Russian diplomat will be expelled from Bulgaria after prosecutors alleged Russian involvement in explosions at several ammunition depots in the Balkan country, the Bulgarian Foreign Ministry said Thursday.

In addition to the Foreign Ministry declaring “one more Russian diplomat persona non grata,” Minister Ekaterina Zaharieva called on Russia’s law enforcement agencies to cooperate with Bulgaria's investigations into the explosions so “the perpetrators will be discovered and brought to justice,” the ministry said in a statement.

The prosecutor general’s office in Bulgaria announced Wednesday that it was investigating a possible connection between four explosions at arms depots around the country and frequent visits by alleged Russian military intelligence operatives to the country in the last decade.

Prosecutors suspect the four explosions were intended to disrupt supplies of ammunition to Ukraine and Georgia, and may be linked to an explosion at an ammunition depot in the Czech Republic in 2014. They also think the blasts may be connected to the attempted 2015 poisoning of Bulgarian arms dealer Emilian Gebrev, for which three Russian nationals have been charged.

Bulgaria, which joined NATO in 2004 and the European Union in 2007, has close historical ties with Russia and continues to be dependent on Russian energy supplies.

Over the last year and a half, Bulgaria expelled seven Russian diplomats whom prosecutors had accused of spying. They included Russia’s military attaché, who was accused of coordinating a military intelligence spy network in Bulgaria.