A Polish man has been arrested and charged with planning to co-operate with Russian intelligence services to aid a possible assassination of Volodymyr Zelensky, authorities said.
Polish prosecutors said the man, named as Pawel K, was allegedly tasked with collecting information about an airport in Poland used by Ukraine's president.
The arrest was made on the basis of Ukrainian intelligence, they added.
Authorities did not specify whether the man actually passed any information on.
He could face up to eight years in prison if found guilty. The suspect is in custody and the investigation is ongoing.
In a statement, Polish prosecutors alleged Pawel K had offered his services to Russian military intelligence. He contacted Russians "directly involved in the war in Ukraine," they added.
They said Pawel K had been tasked with collecting information about security at Rzeszow-Jasionka Airport in south-east Poland.
Before the full-scale invasion of Ukraine, Rzeszow-Jasionka Airport was a small regional airport. But it has since has become a key hub in the vast operation to supply Western military aid to Ukraine.
Military and cargo aircraft from the US and across Europe regularly fly in and out of the airport to deliver supplies to waiting trucks that make the 100km (62 mile) journey to the Ukrainian border.
Ukrainian airspace is closed to most flights, so leaders travelling in and out of the country tend to fly in to neighbouring countries such as Poland and travel on to Kyiv by train.
Mr Zelensky is known to have flown out of Rzeszow-Jasionka on foreign visits. In December 2022, he flew back to the airport after a visit to Washington. Other foreign dignitaries, such as US President Joe Biden, have transited via the airport on their way to Ukraine.
Last year, Polish authorities said they had arrested a group of foreign citizens on suspicion of spying for Russia. They were reported to have installed dozens of cameras, including some around Rzeszow-Jasionka Airport.
On Thursday, neighbouring Germany arrested two alleged Russian spies suspected of planning to sabotage German military aid for Ukraine.
Credit: BBC