A Russian court on Monday found 13 teenagers guilty of carrying out a series of ethnic attacks, including the murder of a well-known chess champion, a court official said.

The Moscow City Court sentenced the 13 to prison terms ranging from 4 1/2 years to 10 years after convicting them of crimes including ethnically motivated assault and murder, court spokeswoman Anna Usacheva said.

The group's oldest member, Ivan Kolinichenko, was ordered to undergo psychiatric treatment in addition to being imprisoned 10 years. The spokeswoman would not say how old he was.

Prosecutor said the group was involved in the October 2007 killing of Sergei Nikolayev, a 46-year-old professional chess player from the Siberian region of Yakutia.

Homemade video of Nikolayev's killing was widely broadcast on Russian TV and Web sites.

Russia has seen an alarming increase in hate crimes in recent years, with skinheads and nationalist groups targeting dark-skinned, non-Slavic-looking immigrants from the Caucasus and former Soviet Central Asia.

Officials have been criticized for downplaying hate crimes and classifying many cases as incidents of hooliganism — a lesser crime.

Hate crime watchdog groups say the number of racially motivated murders is on track to surpass the 2007 total.

Some Russian cultural figures, including one TV journalist, warn that xenophobic attacks might be a byproduct of Kremlin-directed campaigns to encourage patriotism and national pride.