Bulgaria's foreign ministry said Thursday that it would expel a Russian diplomat, a day after prosecutors said they had established links between six Russian nationals and several past explosions at arms depots.

-The Bulgarian foreign ministry declared one more Russian diplomat persona non grata- the ministry said in a statement.

It urged Russia to "fully cooperate" in its probes aimed at "discovering the perpetrators and bringing them to justice".

The EU member -- which used to boast close ties with Russia -- has expelled seven other Russian diplomats and another Russian embassy staff member since October 2019 over various spying and other accusations.

Bulgarian prosecutors said Wednesday they have established links between six Russian nationals who spent time in Bulgaria and four explosions at arms depots in the EU country between 2011 and 2020.

Moscow, in turn, accused Bulgarian officials of trying to outdo authorities in Prague who allege that Russian secret services were behind an explosion in the Czech Republic in 2014.

The Czech accusations sparked a wave of EU-Russia tit-for-tat diplomatic expulsions.

Sofia says the four explosions may be linked to the one in the Czech Republic.

Moscow denies involvement in the 2014 blast.

-Bulgaria wishes to maintain a mutually beneficial relationship on an equal footing with Russia- Thursday's ministry statement said.

It added that it "insists on effective cooperation from the part of Russia to elucidate the facts related to the incidents on our territory," adding that Foreign Minister Ekaterina Zaharieva had already met the Russian ambassador in Sofia.