Police arrested a teenager in connection with the fatal stabbing of an Armenian student on a Moscow subway platform over the weekend, a city prosecutor's official said.
The killing was the latest in a wave of attacks against dark-skinned immigrants from the southern Caucasus regions and former Soviet Central Asia.
Sergei Marchenko, a spokesman for Moscow prosecutor's office, said in televised comments that a 17-year-old boy was detained Monday and had confessed to the Saturday evening killing.
Russian news agencies said investigators had classified the attack as simple murder, but were considering classifying the killing as a hate crime.
The ITAR-Tass news agency said the victim - a 17-year-old Armenian native and Moscow university student - was standing with a group of acquaintances when seven people got off a train and attacked them, stabbing him once in the chest. The victim died on the spot.
The incident prompted sharp criticism from the Union of Russian Armenians, a civic organization in Moscow.
"It's not important what nationality the killed person is. This concerns everyone. This is a problem for all of Russia," union chief Ara Abramian said on Ekho Moskvy radio. "If we have extremism and nationalism, we should call these things exactly what they are and then maybe these incidents won't be repeated."
Law enforcement authorities often classify attacks on minorities as simple "hooliganism" with no racial motivation, fueling the anger of Kremlin critics who say the government does little to stem hate crimes.
Several attacks on foreigners and ethnic minorities have occurred in Russia in the past few weeks, and the country has seen a marked rise in xenophobia and racism in recent years, with rights groups accusing the government of inaction.
Assailants, often young skinheads or other nationalists, have committed hundreds of attacks on foreigners from Africa, Asia and Latin America, dark-skinned immigrants from former Soviet Central Asia and the Caucasus Mountains region, and Jews. Dozens have died.
Rights activists say hate groups are emboldened by what they believe is the authorities' mild approach to prosecuting hate crimes, and complain that neo-Nazi and other extremist literature and propaganda is widely available on the streets and on the Internet.
Also Monday, Russian news agencies reported that a 25-year-old Tajik man was killed and another 25-year-old Tajik was wounded after being attacked in Moscow on Sunday. Prosecutors were investigating the crime as a possible racial attack, the AP says.
Deputy Chairman of the Russian Security Council Dmitry Medvedev said during a meeting with journalists that Kyiv could be Russia's ultimate goal in the special military operation in Ukraine