"Temperatures have been eight to nine degrees (Celsius) higher than normal," Roman Vilfant, head of Russia's Gidromettsentr weather monitoring centre, told Reuters on Tuesday. "The first ten days of January have been very warm."

The Izvestia daily reported that St Petersburg's river Neva, normally locked under ice until spring, had broken its banks and reached the walls of the world-famous Hermitage art gallery.

"March has appeared in mid-winter," said the tabloid Komsomolskaya Pravda, alongside a story about an ice sculpture exhibition being cancelled when the exhibits melted.

Temperatures had climbed to seven degrees C (45 degrees Fahrenheit) in Moscow by mid-afternoon on Tuesday, as compared to lows around - 40C faced by the Soviet defenders of their capital as German troops attacked in 1942.

The ferocious conditions of a Russian winter suffered by invading armies under Napoleon and Hitler have made the country's winters legendary and earned them the nickname "General Winter" among military historians.

But Vilfant said winters in European Russia had grown milder in recent years, and no longer fitted the old stereotype.

"For the last 20 or 30 years winter in the Moscow region has been getting warmer. Compared to the 1900-1960 period, average temperatures have increased by three degrees C and more ... It is now closer to the idea of a European winter," he said.

"It is hard to give a single explanation for this, although you can link it to global warming. However, summers have not been getting warmer, they are the same as they were in the middle of the last century."

But he had good news for Russian winter sports enthusiasts, who have had to cancel trips as snow and ice has melted away.