WARSAW, Poland — Poland has arrested 18 people over the past six months on various allegations of pursuing hostile activities or planning sabotage on behalf of Russia and neighboring Belarus, and at least one was involved in an alleged plot to assassinate Ukraine's president, the interior minister said Monday.

Ten of those arrested since December were directly involved in planning various forms of sabotage, such as arson, across Poland, Interior Minister Tomasz Siemoniak told a news conference.

Polish, Belarusian and Ukrainian nationals are among those arrested in recent months, according to Internal Security Agency communiques.

A Polish man was arrested in April on allegations of being ready to spy for Russia's military intelligence in an alleged plot to assassinate Ukrainian President Volodymyr Zelenskyy, Polish prosecutors have said. The man was allegedly seeking contact with Russians involved in the war in Ukraine and was expected to pass on detailed information about the strategic Rzeszow-Jasionka airport near Poland's border with Ukraine.

Separately, a Ukrainian and a Belarusian man went on trial last month on charges of having been members of a Russian espionage ring that was preparing acts of railway sabotage in Poland in 2023 and monitored railroad routes used for the transport of weapons and humanitarian aid into Ukraine.

The men have confessed to the charges that also included monitoring the security of Baltic Sea ports Gdansk and Gdynia, according to state news agency PAP. If convicted, they could face up to eight years in prison.

The interior minister said acts of sabotage were apparently part of a wider plan that also includes cyberattacks, pushing migrants in Belarus to cross into Poland and threatening the security of a country that has supported Ukraine during Russia's full-scale invasion.

“We have no doubt that on the bidding of a foreign country, Russia, there are some people active who are ready to threaten the life, health and property of the Polish citizens,” Siemoniak said.