Russian authorities have barred 39 Polish bikers from entering the country, accusing them of holding an unauthorized rally at a Polish military cemetery located in the Tver region.

The Mednoye Memorial Complex marks the site of the second-largest massacre of Polish officers and prisoners by the Soviet secret police in 1940, and a Polish War Cemetery was jointly established by Poland and Russia there in 2000.

Over the weekend, pro-Kremlin outlets reported that several Polish bikers had trespassed into the memorial complex to conduct a “torchlight ceremony” and were subsequently taken into custody.

On Sunday, regional police announced that 39 individuals faced charges for unauthorized entry and were issued five-year entry bans. This group reportedly crossed into Russia from Belarus.

An association of Polish motorcyclists known as Stowarzyszenie Kocham Polskę stated it had arranged a prayer service and mass at the cemetery the previous Wednesday, although it did not mention any arrests. They shared images of bikers with torches at the memorial.

The association noted that its members had also visited other execution locations of Polish prisoners in Russia and Belarus in the days leading up to this event.

Stowarzyszenie Kocham Polskę did not respond immediately when asked for comments.

In 1940, the Soviet secret police executed approximately 22,000 Polish officers in locations including the Katyn forest, parts of modern-day Ukraine near Kharkiv, and Mednoye. For many years, the Soviet Union attributed the blame for this massacre to Nazi Germany.

In May, Poland’s Foreign Ministry lodged a protest against the removal of military symbols from the Polish War Cemetery in Mednoye. The cemetery confirmed on its website that the military symbols were taken down due to “violations of federal law.”