MOSCOW – Russian Prime Minister Vladimir Putin pointed at the Soviet model as an example of how various ethnic groups can have friendly ties, drawing a quick retort Monday from the president in a rare sign of friction between the two leaders.

Russia's President Dmitry Medvedev (C) chairs the Security Council meeting at the presidential residence Gorki outside Moscow Dec 28, 2010. The attendees include (L to R) parliament Speaker Boris Gryzlov and Russian Premier Vladimir Putin.[Photo/Agencies]

Dmitry Medvedev, countered Putin by saying that the Soviet experience wasn't exactly a positive one and it can't be repeated, adding that Russia may learn from the US experience.

The public exchange will likely fuel speculation about tensions between the two leaders as the nation approaches the 2012 presidential election.

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Putin and Medvedev have denied any rift between them and said they would decide who would run for president in 2012 so that they don't compete against each other. Most observers expect that Putin, who remains Russia's most powerful figure, will reclaim the presidency.

Speaking at a Kremlin meeting focused on ways to assuage ethnic tensions that spilled into the open during riots outside the Kremlin on Dec 11, Putin said that Russia has failed to learn from the Soviet experience and called for cultivating Russian patriotism.

Speaking immediately after him, Medvedev said that the Soviet experience can't be reproduced.

"Can we repeat what was done during the Soviet period? he said. "No, it's impossible. The Soviet Union was a state based on ideology, and, let's say it openly, quite a rigid one. Russia is different."

"We need to work out new approaches," Medvedev said.

During the Dec 11 riots, soccer fans and racists chanting "Russia for Russians!" clashed with police and beat members of ethnic minority groups from the Caucasus region.

The violence in Moscow raised doubts about the government's ability to control a rising tide of xenophobia, which threatens the country's existence.

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 against Moscow after the 1991 collapse of the Soviet Union.

Putin suggested Monday that the authorities might restore harsh Soviet era-restrictions on movement into big cities like Moscow or St. Petersburg. Such a move would target dark-complexioned people from the Caucasus, who flee their impoverished regions for big cities.

"We went for liberal rules of registration too early," Putin said.

Medvedev, however, warned against trying to isolate ethnic groups. "We can't block people from moving around the country, although we need to control that," he said. "We are a single country, and we must learn to live together."

Medvedev warned that ethnic tensions could break Russia up if the government fails to stem violent nationalism and act more harshly to disperse riots.

"Interethnic conflicts are deadly dangerous for Russia," Medvedev said. "We mustn't allow some dimwits to destroy our common home."

Putin also suggested limiting jury trials, introduced all over Russia in recent years. He said that trials by jury for suspects in murders and other grave crimes should only be held on an inter-region level instead of a local level to prevent acquittals based on clan loyalties.

During his eight-year presidency, Putin steadily rolled back Russia's post-Soviet freedoms, abolishing direct elections of provincial governors and pushing other electoral changes that strengthened the Kremlin's control over Russia's political life. The former KGB officer once described the Soviet collapse as the "greatest geopolitical catastrophe of the 20th century."

Medvedev has been markedly more critical about the Soviet past, trying to cater to a more liberal and educated part of the electorate and improve Russia's image in the West. But differences between the two leaders are mostly limited to style and Medvedev so far has acted as a loyal placeholder for Putin.

Nikolai Petrov of the Carnegie Endowment's Moscow office suggested that Monday's exchange between the two leaders could be aimed to distract attention from a second trial of jailed oil tycoon Mikhail Khodorkovsky. The judge on Monday declared Khodorkovsky guilty of theft in a verdict that could keep the tycoon behind bars for years to prevent him from challenging Putin's power.