In recent weeks Russian forces have fought fierce street battles against Chechen rebels, suffering many casualties. Moscow has been saying since Christmas that Grozny was about to fall, but Chechen rebels hiding out in basements and ruins have resisted stubbornly.

Even now, although the Russian military claims to have penetrated the city centre, it stressed that it would need three to four days to establish control over the shattered city, where up to 40,000 civilians remain trapped in cellars with little food or heat.

Itar-Tass said Russian troops were gradually strengthening their grip on Grozny on the second day of concerted attacks to flush out Islamic rebels. The news agency quoted Russian officers in the region as saying fierce fighting was raging elsewhere in Grozny after a night of heavy artillery and aerial bombardment.

A previous drive to seize the capital ran into trouble in early January when troops encountered fierce resistance from rebels who had dug in while the Russian army was advancing through the Chechen plains. Acting President Vladimir Putin, the strong favourite in early presidential elections to be held on March 26, has said the military will have to take Grozny before moving to eliminate rebel bases in the mountains to the south.

Russian opposition to the war has grown as casualties mount. The soldiers' mothers committee, a charity that promotes servicemen's rights in Russia, claims that 3,000 troops have been killed in the conflict, well above the official figure of 600 dead. General Anatoly Kulilov, who commanded Russian forces in Chechnya in the first half of 1995, yesterday called on the military to halt its advance and consolidate its gains.

The final push to subdue Grozny came as the new Russian parliament opened its first session. Mr Putin urged MPs to end years of bitter wrangling with the presidency and tackle the country's problems. His mere presence in the chamber and his conciliatory speech contrasted vividly with his predecessor, Boris Yeltsin, who fought bitter disputes with parliament throughout his administration.

"The executive power is prepared for fruitful cooperation with the new duma [lower house of parliament]," Mr Putin said. "We must put an end to the policy of confrontation and mutual ambitions."

The duma is due to elect a speaker today, a key position in determining how the legislature handles its daily business. The communists, who dominated the last duma, were fighting to retain control of the post.

But the new duma is dominated by centrists after four moderate parties performed strongly in parliamentary elections in December. MPs are expected to be more willing to implement pro-market reforms and work with the government in tackling Russia's massive economic and social problems.