FILE PHOTO: Polish soldiers patrol along the border fence on the Polish-Belarusian border in Usnarz Gorny, Poland, August 30, 2023. REUTERS/Kuba Stezycki/File Photo
FILE PHOTO: Polish Prime Minister Donald Tusk speaks during the ceremony marking the 86th anniversary of Nazi Germany's invasion of Poland, at the Westerplatte Monument in Gdansk, Poland, September 1, 2025. REUTERS/Lukasz Glowala/File Photo

WARSAW (Reuters) - Poland is closing its border with Belarus on Thursday at midnight local time as a result of Russia-led military exercises taking place in Belarus, Prime Minister Donald Tusk said on Tuesday, amid escalating tensions between Minsk and Warsaw.

Russia and Belarus' large-scale military exercises, known as the "Zapad" drills, have raised security concerns in neighbouring NATO member states Poland, Lithuania and Latvia. "Zapad-2025" (West-2025) will be held in western Russia and Belarus.

"On Friday, Russian-Belarusian manoeuvres, very aggressive from a military doctrine perspective, begin in Belarus, very close to the Polish border," Tusk told a government meeting.

"Therefore, for national security reasons, we will close the border with Belarus, including railway crossings, in connection with the Zapad manoeuvres on Thursday at midnight."

Asked about the duration of the border closure, Interior Minister Marcin Kierwinski said it would only be reopened when the government was sure "there was no more threat to Polish citizens".

The Belarusian Foreign Ministry said it had summoned the Polish charge d'affaires to complain about the border closure which it said "caused significant difficulties". It described the measure as "an abuse of its geographical position".

"The temporary suspension of passage indicates rather an intention to conceal one's own actions than the existence of any threat from Belarus," it said.

Lithuania's border guard said on Tuesday the protection of its border with Belarus and Russia would be strengthened due to the exercises.

STRAINED RELATIONS

Already strained relations between Poland and Belarus have hit new lows since Minsk's ally Russia invaded Ukraine in 2022. Poland has already closed most of its border crossings with Belarus, with only two still operating.

On Thursday, Belarusian media reported that a Polish national had been arrested in Belarus on suspicion of espionage for having documents related to the Zapad exercises.

Tusk said on Tuesday that Poland arrested a Belarusian spy and would expel a diplomat who "supported the aggressive action of the Belarusian state against Poland". He added the arrest was the result of cooperation with the Czech Republic and Romania.

Prague said on Monday it would expel a Belarusian diplomat it accused of espionage, while in Romania, anti-organised crime prosecuting unit DIICOT said it was investigating a 47-year-old Moldovan former senior intelligence agency chief for treason.

The Belarusian Foreign Ministry also denounced the expulsion of the diplomats as "groundless" and "an element of coordinated provocative policy with the Czech side...with the aim of boosting tension in international relations and within the region."

The Zapad-2025 exercises will include drills on the possible use of nuclear weapons and the Russian-made, intermediate-range hypersonic Oreshnik missile, according to the Belarus defence minister.

NATO is holding drills on its side of the border at around the same time. Both Poland and Lithuania began exercises earlier this month, with allied troops taking part.

(Reporting by Alan Charlish, Pawel Florkiewicz, Anna Wlodarczak and Andrius Sytas; Editing by Sharon Singleton and Alex Richardson)