Tusk said Monday that an explosion which damaged a railway line to its close ally Ukraine was an “unprecedented act of sabotage”.

The damage, which authorities have said was discovered on Sunday, directly targeted “the security of the Polish state and its civilians”, Tusk wrote on X.

Poland’s National Prosecutor’s Office said it had launched a probe into what it described as “sabotage of a terrorist nature” that it alleged was committed “on behalf of a foreign intelligence service”.

AFP journalists at the scene of the incident in Mika, some 100 kilometres (62 miles) southeast of Warsaw, found that the tracks were already being repaired.

The area was cordoned off and being guarded by police and railway security guards.

Poland – a NATO and EU member – has become the main hub for transporting military and humanitarian support to neighbouring Ukraine since Russia's full-scale military invasion in February 2022.

Warsaw blames Moscow for what it says are multiple incidents of sabotage since then, including drone incursions and arson attacks, which the Kremlin has angrily denied.

In recent years Poland has restricted the movements of Russian diplomats on its soil, ordered the closure of two Russian consulates, and detained a total of 55 individuals suspected of acting on behalf of Moscow.

Ukrainian solidarity

The explosion was on the rail link running from Warsaw to the Polish city of Lublin and connects to a line serving Ukraine.

“This route is also crucially important for delivering aid to Ukraine,” he added after visiting the site of the incident in Mika, 100 kilometres (62 miles) southeast of Warsaw.

According to Tusk, the damage “was likely intended to derail a train”. An incident was avoided as a train driver alerted specialized services to “anomalies in the railway infrastructure” before stopping the train.

No one was injured in the incident. Tusk also reported another incident that occurred on the same line, where windows in one carriage were shattered, most likely due to a damaged rail.

Interior Minister Marcin Kierwinski said the explosion was triggered via a cable, a fragment of which was found at the scene.

An investigation was immediately launched by the police and special services. “We will catch the perpetrators, no matter who their sponsor is,” Tusk said.

He later said the country’s national security committee, including military commanders and a representative from the presidency, would meet Tuesday.

NATO Secretary General Mark Rutte stated on Monday in Brussels that the alliance remains “in close contact with Polish authorities”.

“The threats to our security are real and growing,” EU chief Ursula von der Leyen said on X in response to Tusk’s post, calling on Europe to “urgently boost capacity to protect our skies and our infrastructure”.

Since the beginning of Russia’s invasion of Ukraine in February 2022, Poland claims to have been the target of sabotage attempts allegedly orchestrated by Russia.

Meanwhile, Ukrainian Foreign Minister Andriy Sybiga expressed his “solidarity with friendly Poland” and promised Ukrainian assistance in the ongoing investigation “if called upon”.

He suggested the incident could be “another hybrid attack by Russia – to test responses”.

The interior minister also mentioned two other incidents reported on the same railway line, which are also being investigated.

According to Kierwinski, several dozen meters (feet) of rail line was damaged near the city of Pulawy, causing a train to stop; and a few hundred meters further, an obstruction was placed on one of the rails.

No accidents were caused in those incidents.