Igor Sergeyev was speaking after a senior spokesman for the Chechen rebels told the BBC that all their fighters had withdrawn from Grozny, having been under attack from Russian forces since last October.

But Sergei Yastrzhembsky, the acting Russian president's aide, said fierce fighting was continuing.

Russian Foreign Minister Igor Ivanov refused to confirm any withdrawal, though he said it was clear that the conflict was going in that direction.

Chechen minister Movladi Udugov said rebels left as part of a planned retreat, as Russian forces closed in on the central districts.

Only a few days ago, the Chechen leader, Aslan Maskhadov, was telling his commanders to remain in Grozny until 23 February - the anniversary of the Russian deportation of Chechens in 1944.

Bloody exodus

Eyewitness reports from Gronzy suggest a large and bloody exodus from the capital.

Chechen fighters and local residents said several commanders were killed when a large contingent of rebels blundered into a minefield on the edge of Grozny.

Mr Udugov said he had been informed of the redeployment by rebel field commander Shamil Basayev.

But reports said the commander had been wounded in fighting and undergone surgery in Alkhan-Kala, near Grozny, on Monday.

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Rebels also reported that the city's rebel mayor Lecha Dudayev, a relative of the former Chechen leader, Zohar Dudayev, had been killed, as had rebel generals Aslambek Ismailov and Khunkarpasha Israpilov.

A BBC correspondent in Moscow says a Chechen withdrawal from Grozny would be a significant victory for the Russians, but they will still be wary. Rebels lost the city in 1995, but retook it in 1996.

Television pictures have showed Russian flags flying over Minutka Square - one of the most hotly contested parts of Grozny.

The square, which offers access to central districts, was the scene of fierce battles in the 1994-96 Chechen war, which ended with a humiliating Russian retreat from the region.

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