Polish prosecutors have arrested a Ukrainian man suspected of collaborating with Russia to sabotage a rail track, they said on Monday.
Poland, a major ally in Kyiv's fight against Russia's invasion, has already charged two other Ukrainians in absentia over the blast on the Warsaw-Lublin line connecting Warsaw to the Ukrainian border.
Poland says those two men - identified as Oleksandr K. and Yevhenii I. - fled to Belarus and wants them extradited.
"The evidence shows that in September 2025, Volodymyr B. drove Yevhenii I. to the area of planned sabotage operations, allowing him to do reconnaissance in the area and choose the place where the explosives would be planted," prosecutors said of the third suspect in a statement published by a spokesperson.
"The investigation continues. Intensive activities are being carried out to identify all other persons who in any form participated in the commissioning, planning, organisation or execution of the sabotage."
Poland is closing the last Russian consulate in its territory and deploying thousands of soldiers to protect infrastructure in response to the incident.
Moscow has denied responsibility for sabotage, citing "Russophobia", and said it would likewise limit Poland's diplomatic and consular presence in Russia.
There has been a wave of arson, sabotage and cyberattacks in Poland and other European nations since Russia's full-scale invasion of Ukraine began in 2022.
