By Christian Lowe

MOSCOW, May 1 (Reuters) Former Soviet leader Mikhail Gorbachev won a Nobel Peace Prize for helping thaw relations between Moscow and Washington. Now he is warning that the two countries could slide into a new Cold War.

After over a decade when the relationship between Moscow and Washington was nearly always upbeat, the mood in the two capitals has turned ''sour'', according to one Western diplomat.

The adversarial attitudes of the Cold War have been resurfacing everywhere from the statements of politicians to the views of people on the streets and the choice of villains in Russian television dramas.

''We have not yet left the past behind: its death grip can be felt everywhere,'' Gorbachev, the last leader of the Soviet Union, wrote last month in the Rossiiskaya Gazeta daily.

''Calls to cool down or even toughen the relations between our countries have become everyday fare in Washington.

''In our country we also have people who -- some with alarm and others with relish -- are bracing themselves for a renewal of the Cold War in some sort of new format.'' The irony is that on the business front, the mood could not be further removed from the Cold War.

Nearly every month, a new Russian company lists on a New York bourse, U S banks are putting up their signs on Moscow's streets and investors are clambering over each other to get their hands on Russian stocks.

SUMMONED The atmosphere is very different from the one five years ago when U.S. President George W. Bush first met Russia's President Vladimir Putin. They seemed to hit it off and their rapport set the tone for strong ties.

''There is a sour mood that you will see in Washington about the relationship and you know that you will find the same view (in Moscow),'' said the Western diplomat.

That mood could make for an awkward few days in July when Putin hosts Bush and other world leaders for a summit of the Group of Eight industrialised countries in St. Petersburg.

On April 18, U.S. Ambassador to Moscow William Burns was called to the Russian foreign ministry. Moscow was upset because, it said, a Washington think-tank had given Chechen separatists a platform to voice their violent philosophy.

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