The Belarusian defence ministry said on Sunday it had summoned a Ukrainian military attache to protest against what it called repeated violations of Belarus airspace by Ukrainian aircraft.

Relations between Belarus and Ukraine have plummeted since last year, when Russia sided with Belarusian President Alexander Lukashenko during street protests and Lukashenko in turn became more vocal in his support for Moscow against Ukraine.

Belarus handed a note of protest to the Ukrainian official, the defence ministry said in a statement on its website, citing a violation of its airspace on Saturday. “The military attache was informed that the Ukrainian side is avoiding a dialogue to resolve disputes... which is very worrying,” the ministry said.

Belarus said on Saturday that a Ukrainian military helicopter had flown 1km into Belarusian territory during manoeuvres. A spokesperson for Ukraine’s border guard service denied the accusation.

Ukraine’s foreign ministry did not immediately reply to a request for comment on Sunday.