NAZRAN, Russia (AP) _ Russian warplanes and attack helicopters streaked across the sky over Grozny today, while Russian and separatist forces battled to control the capital of breakaway Chechnya.

The Russian government said the presidential palace in downtown Grozny had been blockaded and reported heavy fighting today around the building, a key objective of the Russian forces.

Russian troops seeking to capture Grozny encountered ferocious resistance from Chechen rebels over the weekend, prompting Russia's defense minister to call for back-up troops. Russian forces pounded rebel positions in Grozny on Sunday with tanks, rockets and artillery.

Russia's Independent TV reported fierce house-to-house fighting in some areas and said Russian tanks had been cut off from their support units. It showed footage of wounded soldiers, and the bodies of Russian soldiers in the streets.

Anti-war Russian lawmakers in Grozny said they had seen the bodies of many Russian soldiers in burned-out tanks.

Vladimir Zhitarenko, a 54-year-old correspondent for the Krasnaya Zvezda military daily, died Sunday after being shot in the head, the Russian Defense Ministry said today.

He was the second journalist to be killed covering the Chechen war. American freelance photographer Cynthia Elbaum, 28, was killed during a rocket attack on Grozny on Dec. 22.

The whereabouts of Chechnya's president, Dzhokhar Dudayev, was unclear. The Russian government claimed Dudayev had fled the palace and taken refuge in a bunker on the outskirts of the besieged city, but Independent TV said Dudayev was not there.

Black smoke rolled out of the burning Lenin oil refinery on the edge of the city, a day after the Russians began their all-out assault on the capital of the secessionist, mostly Muslim republic of 1.2 million. Much of the devastated city was blanketed in smoke and the snow was stained black up to 80 miles away.

Tank, rocket and small-arms battles raged around the presidential palace and the railway station several blocks away.

Defense Minister Pavel Grachev said Russian reinforcements entered Grozny on Sunday, and vowed to ``cleanse'' the city of rebels by the end of the week.

Near the town of Urus-Martan, 12 miles to the southwest, villagers said they saw several hundred Russian paratroopers and at least a dozen attack helicopters.

Chechen fighters were headed in their direction.

Up to 40,000 Russian troops entered Chechnya on Dec. 11 to restore Russian authority and end what President Boris Yeltsin called an illegitimate, criminal regime. Tens of thousands of people have fled the fighting, and hundreds of civilians and soldiers are believed to have been killed.

``We have to use force; there is no other way to rescue the population,'' Russian Foreign Minister Andrei Kozyrev said Sunday on NBC's ``Meet The Press.'' ``This is not an independence movement. It is just a criminal gang.''

But the war is unpopular both at home and abroad.

``Constitutional order cannot be restored with artillery,'' Gen. Alexander Lebed, a top-ranking Russian officer and one of many military critics of the war, told Independent TV on Sunday.

In Washington, incoming Senate Majority Leader Bob Dole said the military actions could jeopardize Russian democracy and U.S. aid to Russia.

``This is a no-win situation for Yeltsin,'' the Kansas Republican said on CBS' ``Face the Nation.'' ``It's an indication that democracy may be on the brink.''