President Vladimir Putin said on Friday the United States' "unipolar" vision of the world had failed and sanctions imposed on Russia over the Ukraine crisis would have a boomerang effect on the West.

In a speech at a business forum billed as Russia's answer to Davos, Putin set out plans to revive the country's flagging economy, including relying less on energy exports.

But he also appeared to try to drive a wedge between the United States and Europe by thanking European businesses for taking a more "pragmatic" approach over the sanctions than U.S. firms.

The European Union, heavily reliant on Russian gas supplies, has been more reluctant than Washington to impose tough sanctions on Russia.

"The world has changed," Putin told the annual St Petersburg International Economic Forum. "The unipolar vision of the world ... has failed."

A senior government official said at the forum in Russia's second-biggest city on Thursday that the sanctions, mainly imposing visa bans and asset freezes on individuals and companies close to Putin, were starting to have a serious effect.

The country is sliding into recession and capital flight has accelerated this year as the crisis in Ukraine, including Russia's annexation of the Crimea peninsula from its neighbor, caused the biggest East-West standoff since the Cold War.

He reiterated a promise that the world's top oil and gas producer should diversify from energy exports, which provide about 25 percent of gross domestic product, and said Russia must boost major domestic banks and industries.

Putin also said there was a plan to create a state fund to help replace imports from Western countries with domestic production.