MOSCOW — A thousand Cossacks, who formed a feared military force in czarist times, will help police patrol the southern Russian region hosting the 2014 Winter Olympics in the Black Sea resort of Sochi, charged with preventing an influx of labor migrants from the Caucasus.

The planned deployment of the Cossacks, announced by the governor of the Krasnodar region, has been harshly criticized in Russia, with some warning that it will lead to a rise in ethnic tensions and even hate crimes against mostly dark-complexioned Muslim migrants.

The Cossacks will be unarmed but still wear uniforms identifying them as adherents of a military force that still celebrates its pre-Soviet role as a defender of Russia’s borders.

Their mission beginning Sept. 1 will be to deal with migrants whose “behavior is not always legal, not always right,” Konstantin Perenishko, deputy head of the Kuban Cossack Army, said Monday.

Gov. Alexander Tkachyov announced the deployment of the Cossacks in a speech to police officers last week.

“What you can’t do, a Cossack can,” Tkachyov said. He said the Cossacks would not be as restrained as police in maintaining public order and enforcing migration laws.

He said the presence of the Cossacks would deter non-ethnic Russians from coming to Krasnodar, an agricultural region.

Tkachyov appeared most concerned about Russian citizens from the multi-ethnic Caucasus region, which has been plagued by an Islamic insurgency and economic woes since the start of the first Chechen separatist war in 1994.

Ethnic Russians treat Caucasus natives with increasing xenophobia and hostility. Migrant workers from former Soviet republics in Central Asia, Armenia and Azerbaijan also face increasing discrimination.

Cossack paramilitary communities spearheaded czarist Russia’s expansion and were notorious for anti-Semitic pogroms that triggered mass Jewish migration to the West.

In the Soviet era, Cossacks were persecuted and purged for their resistance to Communist rule. The post-Soviet revival of their squads and parades is often seen as harmless theatrics.