Even more of a nightmare if that visitor happens to be Russian Prime Minister Vladimir Putin, who cultivates a fearsome tough-guy image at home and has raised hackles in the West with his assertive foreign policy.

Katya Kazakova, a pupil at a boarding school in Moscow for the daughters of Russia's military, looked like her day was ruined when her voice lost all contact with the music in a rendition of a wartime song in front of Putin.

But luckily for Katya, Putin cast aside his tough image and rescued her by joining her in a duet of the World War II Soviet song "The Dug Out", pictures broadcast on the NTV television channel showed.

"The fire is pulsing in a cramped stove/ The resin on the firewood is like a tear/ And in a dugout an accordion is singing/ About your smile and your eyes," Putin sang, showing a surprisingly soft and melodious voice.

Putin had earlier shown his good mood ahead of Saturday's holiday to celebrate the Soviet victory in World War II by drawing a smiley face on the classroom whiteboard, television pictures showed.

Russia's judo-mad strongman has over the last years earned a reputation for revealing hitherto unknown interests and talents.

Famous official pictures taken during his presidency showed him fishing with a muscular naked torso that would impress any fitness fanatic while last year he fired a tranquilising dart at a tiger on a trip to the Far East.

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