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.[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. 

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.