Russian police on Tuesday arrested dozens of people suspected of planning a racist rally near the Kremlin walls, as authorities looked to avert a repeat of last month's riots by ultra-nationalists who objected to the presence of non-Slavs in the country.

The arrests came after jittery police cordoned off part of a public square outside the Kremlin and evacuated a nearby shopping mall.

At least 30 police trucks lined up on Manezh Square in response to internet threats by ultra-nationalists to repeat the Dec. 11 riots, in which 5,000 people chanted "Russia for Russians" and beat dark-skinned passers-by. The riots were a reaction to the killing of a white Russian soccer fan during a fight with people from the south of the country. The violence left more than 30 people wounded and raised doubts about the government's ability to stem a rising tide of xenophobia. Days later, police detained 800 people in the capital and other cities to prevent further violence.

An Associated Press television crew saw at least 20 people taken to police vans Tuesday after a police document check, including one person wearing clothes bearing the initials of a well-known nationalist organization, the Movement Against Illegal Immigration. Russian news agencies said up to 100 people were detained.

Kremlin critics accuse the authorities of fomenting social disorder to justify a crackdown on the opposition before presidential elections in 2012. Since the unrest, Prime Minister Vladimir Putin has proposed restricting the movement of nonresidents into big cities and President Dmitry Medvedev has called for mandatory prison sentences for people participating in unauthorized rallies. Moscow's police chief Vladimir Kolokoltsev has said liberal values come a distant second to public order.

Critics, including former Deputy Prime Minister Boris Nemtsov, have said the measures proposed by Putin and Medvedev could cripple attempts to hold peaceful anti-government demonstrations.

Putin and Medvedev have said one of them will run for president in 2012, but they won't compete. It continues to appear that Putin, thought to retain real control over Russia since his eight-year stint as president ended in 2008, will run again.

While ethnic Russians make up four-fifths of Russia's population of 142 million, the country is also home to about 180 ethnic groups. The Caucasus region, with its mountainous terrain and isolated valleys, hosts at least 100 ethnicities including Chechens, who have waged two separatist wars since the 1991 collapse of the Soviet Union.

AP reporter David Nowak contributed to this report.