Russian police have detained 25 men wearing black field overcoats with images of Nazi swastikas in Moscow Sunday, the RIA Novosti news service reported.

The arrests coincided with Unity Day, a national holiday established by the Kremlin in 2005 to replace commemorations of the Bolshevik Revolution.

“The Moscow police have detained 25 people in black field overcoats with the swastika near the Tretyakovskaya metro station who were chanting slogans,” a police spokesman said.

The detainees have been taken to a police station where the charges of administrative offences will be brought against them, the spokesman said.

Thousands of nationalists marched through the Russian capital, chanting slogans including “Moscow is a Russian city” to express their resentment of dark-complexioned migrants from the Caucasus and Central Asia.

For much of his first two presidential terms in 2000-2008, Vladimir Putin cultivated nationalist sentiment.

By the end of his second term, however, racist violence had skyrocketed and more than 100 immigrants were murdered yearly from 2007 to 2009, according to the Sova Center, which monitors far-right groups.

A crackdown began in 2010 when thousands of nationalist soccer fans clashed with riot police outside the Kremlin. Since then, convictions for violent hate crimes have risen sharply, according to Sova.

The most prominent nationalist groups, including the Slavic Union and the Movement Against Illegal Immigration, were banned for extremism, however their leaders have managed to start other groups with similar ideologies.