The Polish foreign ministry has banned a biker gang linked to Russian President Vladimir Putin from entering the country.
The Night Wolves had planned to enter next week as part of a ride across Europe to commemorate the 70th anniversary of World War Two.
Polish Prime Minister Ewa Kopacz had called the plan a "provocation".
The Night Wolves' vice-president, Felix Chernyakhovsky, has insisted the bikers still intend to make the trip.
"Everything remains the same. We're starting tomorrow as planned," he told Interfax news agency.
The Night Wolves are subject to US sanctions for alleged active involvement in Crimea and for helping to recruit separatist fighters for Russian-backed rebels in eastern Ukraine.
Russia's foreign ministry said it was "outraged" at Poland's decision.
'Kremlin's Hells Angels' - by Adam Easton, BBC News, Warsaw
The Night Wolves' planned road trip through Poland stirred such controversy because of the group's close association with Vladimir Putin and its support of Moscow's annexation of Crimea and Russian-backed separatists in eastern Ukraine. They are viewed in Poland as the "Kremlin's Hells Angels".
The day after news of the trip appeared earlier this month many Polish newspapers illustrated the story with a photograph showing a sunglass-wearing, helmetless Russian president riding an enormous three-wheeled Harley-Davidson Lehman Trike with the club in Crimea in 2010.
A Facebook page entitled "No to the Russian bandits' ride through Poland" quickly garnered support from more than 10,000 people.
The page's co-host Jarek Podworski, a biker from Krakow, told me the Night Wolves were not motorcycle enthusiasts but criminals, some of whom had taken part in the fighting in eastern Ukraine. Besides, he added, Poles remembered the Soviet occupation of Poland.
Warsaw has been a strong critic of Moscow's actions in Ukraine.
The Polish foreign ministry said three other Russian biker groups would be allowed into the country.
But it said it was notified of the group's plans only on Monday, and without details of the route or number of participants.
The ministry added that it had informed the Russian embassy in Warsaw that the lack of information meant "it could not ensure proper security for the participants".
However, Russia's foreign ministry said in a statement: "It is clear that the decision that was taken has a political motive."
The Night Wolves intend to cross several countries, following a path taken by the Red Army in World War Two, with the aim of arriving in Berlin in time for 9 May Victory Day celebrations in Moscow.
The 6,000km (3,720 mile) road trip would take them through Russia, Belarus, Poland, the Czech Republic, Slovakia and Austria, before reaching Germany.