The Slovak foreign ministry says it is “disturbing” that the Night Wolves – a Russian nationalist biker gang close to President Vladimir Putin – now have a base in Slovakia.
The base has old military vehicles and lies in Dolna Krupa, a village 70km (44 miles) from the capital Bratislava.
The Russian government calls it the Night Wolves' “European headquarters”.
The bikers are under US sanctions, accused of providing military help for the pro-Russian rebels in Ukraine.
Slovak foreign ministry spokesman Peter Susko told the BBC that the Night Wolves' activities would have to be “carefully monitored”.
“We think the influence of their members is harmful, especially in spreading their opinions that strive to rewrite history,” he said in a phone interview.
When asked to specify those controversial opinions he said “that Crimea is, was and will be Russian, that Stalin was a great…
