Belarus' KGB state security service spokesman Dmitry Pobyarzhin speaks during a briefing in Minsk, Belarus November 20, 2017. REUTERS/Vasily Fedosenko

KIEV (Reuters) - Ukraine said on Tuesday it had expelled a Belarussian diplomat in a tit-for-tat move linked to allegations from Belarus that the Ukrainian defense ministry had set up a spy ring in Minsk.

Belarus’s KGB state security service said on Monday it had arrested a Ukrainian journalist and declared a Ukrainian diplomat persona non grata due to their alleged involvement in espionage.

“The Ukrainian foreign ministry has also made the decision to declare a Belarussian diplomat persona non grata and he has already left the country,” Ukrainian foreign ministry spokeswoman Mariana Betsa said by telephone.

Betsa said the diplomat was a first secretary in the embassy in Kiev but declined to name him or her. The Ukrainian defense ministry has denied the KGB’s allegations.

Minsk-based Ukrainian journalist Pavlo Sharoyko was arrested in October and has since been charged with being an undercover intelligence officer by the KGB.

Reuters has not been able to reach him for comment.

The case puts further pressure on relations between Minsk and Kiev that were tested earlier this year when Belarus hosted large-scale joint military exercises with Russia.

September’s Zapad-2017 (“West-2017”) war games unnerved Ukraine and NATO member states on Europe’s eastern flank, which feared the exercises could be a rehearsal or cover for a real offensive.