The Committee of Soldiers' Mothers says it estimates that 3,000 soldiers have been killed and 6,000 injured in the current campaign.

The allegation came as Federal troops launched another intensive bombardment on Grozny.

Plumes of smoke and thick dust have been seen rising over Grozny's central and eastern districts.

Russian military sources say that the intense artillery and air attacks were providing cover for advancing ground troops.

There are also reports of fierce fighting in the south of the republic.

Death toll deception

"All this time there have never been comprehensible figures about losses," Valentina Melnikova the head of the Committee of Soldiers' Mothers said.

She said new information had reached her organisation from regional committees that suggested the death toll was far higher than had previously been estimated.

BBC Moscow correspondent William Horsley says the committee's claims are a serious challenge to the credibility of the Russian government.

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On the ground, fierce fighting is reported in and around Grozny. Federal forces and rebels report inflicting large numbers of casualties on their enemy.

Lieutenant Colonel Konstantin Kukharenko, a Russian military spokesman, has said that Chechen rebels are moving their best fighters out of Grozny in the face of a Russian push in the city.

He also said that the rebels in the Shroi area were trying to break through Chechnya's eastern border into Dagestan.

Chechen commanders have said they are still in control of large areas of the capital and have beaten back a Russian attack near a canning factory in the north-west of the city.

Mistakes

On Saturday, acting Russian President, Vladimir Putin admitted that senior Russian military commanders had made mistakes in Chechnya, but insisted the campaign was going smoothly.

Mr Putin told Russian television that time and patience would be required to win the war.

The Russian leader stressed that civilians would not be sacrificed for military gains, because local support was critical in the struggle to overcome the rebels.

International attention

The Russian army's treatment of the Chechen civilian population is likely to come in for more criticism form the Council of Europe.

A European delegation, led by the British peer Lord Russell-Johnston, is expected to meet Mr Putin at the Kremlin on Monday as part of a five-day fact-finding tour.

The delegation is scheduled to visit the Caucasus and tour Russian-controlled areas of Chechnya.

The European Union is also due to meet in eight days to consider sanctions against Russia over its campaign.

An official from Portugal, which currently holds the EU presidency, indicated that the Union would reconsider its aid to the former Soviet states and its general relationship with Moscow.

"We cannot close our eyes to Russia's mistakes," Junior Foreign Minister Francisco Seixas Da Costa said.

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