Liverpool supporters were attacked by hooligans both before and after their Europa League match at Zenit St Petersburg on Thursday.
A report on St Petersburg's Peter TV channel said that on the night before the last 32 first-leg tie - which the Reds lost 2-0 - a 40-strong group had attacked travelling fans as they emerged from a bar in the city.
Liverpool supporters were forced to take shelter inside before security staff used baseball bats to disperse the attackers. Local media reports said nobody was seriously injured in the incident.
Supporters also said they had been attacked on metro trains as they travelled to and from the Petrovsky Stadium, with some also claiming to have been attacked inside the ground.
In the days before the game, Zenit officials had said they were working to ensure a safe atmosphere at the match, at which there was a high police presence, after Liverpool raised concerns about potential racism.
A statement from the Russian club issued earlier in the week said: "The club's personnel have been working hard so that the players and fans alike would enjoy the match.
"Zenit have always condemned any form of racism. We hope our opponents share the same principles and tomorrow we all be treated to a great football match and passionate crowd support."
Liverpool raised concerns because supporters in St Petersburg - a city with strong links to nationalist right-wing politics - have become notorious for racism.
In December, the club's largest fan group demanded that no black or gay players should play for Zenit, but the Landscrona group later insisted its message was misrepresented.