"Unidentified people injured Kabardino-Balkarian Culture Minister Zaur Tutov in a sporadic conflict at 21.30 Moscow time Saturday," Moscow prosecutors said, adding that they had opened investigation into the incident.
They also said that Tutov had arrived at a hospital an hour later with a cheekbone fracture and other injuries, and was still in the hospital.
The Kabardino-Balkarian president's press service said Tutov, also a famed baritone, had been attacked by 15 people who had shouted "Russia for Russians!"
Prosecutors said other versions, except ethnically motivated violence, would be investigated as well.
The government of the largely Muslim Caucasus republic also accused police that had arrived at the scene of reluctance to capture the attackers and demanded a thorough investigation.
Attacks by skinheads and youth gangs on people with non-Slavic features have become frequent in Russia in recent years.
The central Russian city of Voronezh alone has seen at least seven apparently racially motivated killings over the past six years, including the murder of a Peruvian student in October last year.
On January 11, 2006, Moscow witnessed a shocking attack on a synagogue by a 20-year-old man who stabbed nine people with a hunting knife.
These incidents have prompted Russian and foreign human-rights groups to raise concerns over the alarming spread of xenophobic attitudes in the country.