The unsanctioned demonstration of football fans protesting the death of Spartak Moscow supporter Yegor Sviridov left at least one person dead and 29 injured, a police source said.
"According to preliminary data, one person injured at the unsanctioned demonstration has died. The police are checking this information," the source told RIA Novosti.
However, the Moscow interior affairs department did not confirm this report.
The source also said 29 people were hospitalized with injuries adding that ambulance cars remained on duty on Moscow streets.
Some 5,000 young people, mainly football fans and members of nationalist organizations, protesting Sviridov's death gathered on central Moscow's Manezh Square. About 2,000 protestors gathered in St. Petersburg. They ignored police demands to disperse and clashes broke out.
The police detained 65 football fans in Moscow and 60 in St. Petersburg.
Russian Interior Minister Rashid Nurgaliyev said that the clashes were provoked by nationalists who joined the demonstration of football fans.
The minister also said that "nobody will avoid responsibility" for the death of Sviridov reiterating the pledge of Moscow police chief Vladimir Kolokoltsev who promised a thorough investigation of this tragic accident during negotiations with football fans.
Kolokoltsev also said that policemen did not use weapons on the Manezh Square despite a threat to their lives.
According to Nurgaliyev, several policemen were hospitalized after the demonstration.
Sviridov, 28, was killed earlier this week during a mass brawl between football fans and internal migrants from the North Caucasus in north Moscow.
Police have already detained a man suspected of shooting him four times with a gun firing rubber bullets and two other migrants suspected of participating in the brawl.
MOSCOW, December 11 (RIA Novosti)