The Nobel prize winning Medecins Sans Frontieres has appealed to US President Bill Clinton to step up pressure on Moscow to change its behaviour.

It says human rights violations are worsening since Russia announced a new policy of detaining all Chechen males between 10 and 60 on suspicion of being rebels.

Amnesty International and Human Rights Watch also supported the French aid organisation.

Amnesty said civilians left in Grozny were running out of supplies.

It is unclear how many civilians are trapped in Grozny. Russian authorities have said about 20,000 people are still in the devastated city, but Chechen fighters say the number is closer to 40,000.

He said: "We are not calling on the United States to become a guarantor or a mediator in this case, but if they actually express this wish to become one we would only welcome it.

"The United States has tremendous influence in Europe as well as elsewhere. It can influence the situation."

The US has so far ruled out such a role but State Department spokesman James Rubin said: "We don't believe that the result of force is going to be the melting away of resistance.

"We believe that the Russians are in a cul-de-sac."

Strategic road

But in Chechnya, Russia reported that it was recapturing towns and villages lost to the Chechen rebels at the weekend.

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Russian forces say they are continuing to push further into the Chechen mountains and that paratroopers had taken control of a strategic mountain road, cutting off a rebel supply route.

Reinforcements were also sent to troops surrounding Vedeno, a large town deep in the mountains, and warplanes bombed rebel bases nearby and in the Argun gorge area northwest of Sharoi, the Itar-Tass news agency reported.

Russian military commanders say federal forces have managed to claw back Shali, Gudermes and Argun, and that the policy of not allowing males over 10 and under 60 to leave Chechnya is being enforced.

Meanwhile, Russian Defence Minister Igor Sergeyev pledged to continue the campaign to capture Grozny, as fierce street battles continued in central parts of the city.

He was also quoted as saying that in one town, Urus-Martan, Russian soldiers had found tonnes of explosives similar to those which killed about 300 people in attacks on Russian apartment blocks last year.

On Wednesday, Russian helicopter gunships supported ground troops attacking Grozny.

The Russian offensive followed a self-imposed truce which coincided with the Orthodox Christmas and the end of the Muslim holy month of Ramadan.

At the weekend Russia suffered its worst setback of the four-month campaign with devastating rebel counter-attacks inflicting heavy losses and humiliation on Russia's military command.

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