Moscow police have detained an 18-year-old male suspected of posting a petition on a popular online social network to cancel the city's esteemed celebration of the surrender of Nazi Germany on May 9.
The suspect, who police described as an active participant in an ultranationalist youth movement, was detained in northern Moscow on Monday following an investigation that linked him to an apparent pseudonym, police said in a statement.
Ultranationalist movements in Russia often employ neo-Nazi ideology, even though the Soviet victory over Nazi Germany in World War II is a huge source of national pride for most Russians.
Police allege that the teenager posted material online that was "extremist and incited interethnic strife" and have opened a criminal case on a charge of "inciting hatred or hostility," the statement said.
The teen has been released from custody on the condition that he not leave town while the case is ongoing. But if charged, he faces up to two years in prison, according to Article 282 of Russia's Criminal Code, which was cited in the police statement.
Russia's anti-extremism law, enacted in 2002, has generated a great deal of controversy because its vague definition of what constitutes "extremism" enables the law to be arbitrarily used.
Last month prosecutors in the Siberian region of Krasnoyarsk issued extremism warnings to two publications for publishing photos of a monument that had been vandalized with drawings of swastikas.
A publication that receives two warnings for extremism can be shut down by the authorities.
Last year the popular opposition-focused newspaper Novaya Gazeta was warned by Russia's media watchdog to delete an article from its website that compared the policies of Russian lawmakers to those of Adolf Hitler.