Fierce fires were reported to be burning at an oil refinery and ammunition dumps in the besieged capital.

Reconnaissance photographs showed about 20 separate fires across the city after intensive strikes by the Russian air force.

A BBC correspondent at the Russian operational headquarters in the region said Moscow was hoping that penetration bombs dropped from the air would destroy Chechen fortifications that have resisted artillery assaults.

Russian TV, quoting the Defence Ministry, said special forces trained in urban warfare were leading the ground assault on Grozny.

A Russian army spokesman said that almost 100 rebels had died in the latest phase of the offensive.

Critics of Moscow

The attack came as officials from the Council of Europe prepared to fly to the North Caucasus on Tuesday to meet regional leaders.

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David Russell-Johnston, leader of the delegation, met Russia' acting President, Vladimir Putin, on Monday, but pleas for a ceasefire were dismissed by Moscow.

Mr Putin called on Western nations to judge Russia on the basis of facts, not propaganda.

On Tuesday, the delegation will meet Ingushetia's President Ruslan Aushev - a critic of Moscow's policies in the region.

His republic has had to deal with an influx of more than 200,000 Chechen refugees.

The Council of Europe delegation is on a fact-finding mission ahead of a special debate about Chechnya, scheduled for 27 January.

Lord Russell-Johnson says some of the 41 member states are concerned at the killing in Chechnya, but that talk of Moscow's suspension from the body is premature.

Rebel resistance

Russian military commanders said they expected to have Grozny under their control by early February.

Thousands of civilians are understood to be trapped in Grozny as the battle rages around them.

Many of them are too old or too frail to leave, and are hiding in cellars hoping to survive the bullets and the bombs.

There are also reports of fierce fighting in the south of the republic. The rebels say they are resisting Russia's onslaught and will continue to do so.

At the weekend, Mr Putin stressed that civilians would not be sacrificed for military gains, because local support would be critical in beating the rebels.

New rulers

Moscow says it has already started moving elements of a pro-Russian administration into Chechnya's second city of Gudermes.

And Russian Deputy Prime Minister Nikolay Koshman said a prominent pro-Moscow Chechen, Sapyan Makhchayev, would be made head of a provincial administration for Grozny, the Russian RIA news agency reported.

Mr Koshman, the agency reported, said: "As most of Grozny has been destroyed, we must be ready to start reconstructing municipal services in the town in no time after the capital is liberated."

Moscow moved troops into Chechnya last September after blaming separatist militants for incursions into Dagestan and bomb attacks in Russian cities.

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