The detention brings the total number of people rounded up in an espionage probe to 15, the interior minister says.

A hub for Western military supplies to Ukraine, Poland says it has become a key target of Russian spies and it accuses Moscow of trying to destabilise it.

“The Internal Security Agency has detained another member of the spy network working for Russian intelligence,” Mariusz Kaminski said on Monday in a post on Twitter.

“The suspect kept surveillance of military facilities and seaports. He was systematically paid by the Russians.”

The Russian embassy in Warsaw did not immediately react to the development.

Ukrainian citizen

Prosecutors said in a statement that the individual arrested was a Ukrainian citizen who had been in Poland since 2019 and that he could face up to 10 years in prison if found guilty.

He will be kept in pre-trial detention, prosecutors said.

In June, Poland detained a Russian professional ice-hockey player on spying charges.

Russia said at the time it had demanded an explanation from Poland over its arrest of Russian citizens.

In March, Poland said it had broken up a Russian espionage network and detained nine people it said were preparing acts of sabotage and monitoring rail routes to Ukraine.

The following month Poland said it was introducing a 200-metre (218-yard) exclusion zone around its Swinoujscie Liquefied Natural Gas (LNG) terminal, citing concerns over Russian espionage.

Prosecutors said on Monday that further arrests as part of the investigation could not be ruled out.