Polish Prime Minister Donald Tusk said on Wednesday Russia had planned acts of "air terror" against airlines worldwide, accusing Moscow of staging sabotage and diversion on Polish soil and beyond.
He made the declaration while hosting neighbouring Ukraine's President Volodymyr Zelensky for talks in Warsaw, just days before US President-elect Donald Trump's inauguration.
EU and NATO member Poland has been one of Ukraine's staunchest allies since Russia launched a war against Kyiv in February 2022.
"Poland plays a key role in Europe in countering the acts of sabotage and diversion that Russia is organising, and not just on Polish territory," Tusk told reporters.
"Russia had planned acts of air terror, and not only against Poland but against airlines all over the world," he added.
In November, Lithuania carried out arrests as part of a criminal probe into incendiary devices sent on Western-bound planes.
According to Polish and Lithuanian media, the devices, including electric massagers implanted with a flammable substance, were sent from Lithuania to Britain in July and could be behind a lorry fire outside Warsaw.
The Lithuanian president's chief security adviser blamed Moscow for the incidents.
UK anti-terrorism police in October said they were investigating how a parcel burst into flames at a depot earlier this year, after a similar case in Germany blamed on Russia.
'Speed up' Ukraine's EU accession
Tusk also pledged that Poland, which currently holds the rotating six-month presidency of the European Union, will speed up Ukraine's process to join the bloc.
"The Polish presidency will break the impasse that has been evident in recent months," Tusk said.
Zelensky told reporters that "the sooner Ukraine is in the EU, the sooner Ukraine becomes a member of NATO... the sooner the whole of Europe will get the geopolitical certainty it needs".
The Ukrainian president has been holding a flurry of meetings with his country's backers ahead of Trump's return to the White House.
The Republican has promised to bring a swift end to the fighting when he takes office next week, raising fears in Ukraine that it will be forced to make major territorial concessions in exchange for peace.
Polish President Andrzej Duda, who also met with Zelensky on Wednesday, reiterated that Ukraine must be present at the table during any eventual peace talks.
"There can be no talks regarding Ukraine, the war's end, Ukraine's independence and sovereignty, without Ukraine's participation," Duda told reporters.
'Problem to resolve'
Both Duda and Tusk also spoke with Zelensky on resolving a decades-long dispute over the World War II-era Volyn killings of Poles in what is now western Ukraine.
Tusk, whose ruling pro-EU alliance faces a presidential election in May, is under pressure from the national conservatives at home to secure exhumations of the massacre's victims.
On Friday, Tusk had hailed "a decision on the first exhumations of Polish victims" but both Kyiv and Warsaw remained tight-lipped on details of what has been agreed.
"There is a pretty obvious problem to resolve, which is the need of Polish families to bury their loved ones with dignity," Tusk said alongside Zelensky on Wednesday, adding that the two sides "understand each other on the matter".
Neither side specified what concrete actions had been taken.
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