The assault was a new stage of an offensive against Chechen separatist fighters that began after President Boris Yeltsin was re-elected on July 3 and defied calls by the Russian Parliament for an end to the violence.
Rebel Chechen spokesman Movladi Udugov said by telephone that five Chechens had been killed and 18 wounded since Moscow launched the assault Saturday near Shatoi, about 50 km (30 miles) south of the regional capital Grozny.
"Fighting resumed this morning," Udugov said, identifying the settlement of Borzoi as the main target of the attack. "(On Saturday) they brought in paratroopers and used aviation, artillery, missile-launchers and about 100 armored vehicles."
He said a Russian helicopter and a fighter-bomber had been shot down, but his comments could not be confirmed.
Interfax news agency quoted a source in Grozny as saying a "real war" was under way near Shatoi and that the Russian death toll was six. A Russian military spokesman in Grozny, Igor Melnikov, put the figure at four dead and four wounded.
Melnikov said 60 rebels had been killed and Udogov said more than 150 Russian soldiers had died. Each side has wildly exaggerated the other's casualties in 19 months of fighting that has killed more than 30,000 people.
The intensity of the battle in the wooded, mountainous region near Shatoi could not immediately be determined independently.
Yeltsin, who sent troops to the rebellious southern region in December 1994 to try to crush its separatist drive, signed a cease-fire agreement with rebel leaders in late May to boost his chances of winning a second term.
The truce is still officially in force but attacks on rebel-held villages in southern Chechnya in the last two weeks have all but destroyed it. Each side blames the other for the upsurge in fighting.
Russia's lower house of Parliament, fearing violence could spiral, approved a resolution Friday urging Yeltsin to end the fighting and restart peace talks. But he has ignored similar calls in the past and the resolution was non-binding.
Melnikov said up to 300 separatist fighters were holed up near Shatoi. Such a concentration of fighters would make it a major base for the rebels, who are now mainly confined to the region's southern mountains.
Udugov denied the rebels had a base in Borzoi, although up to 150 civilians there had formed self-defense units that he said were permitted under agreements signed with Moscow.
In other weekend violence, Itar-Tass news agency said five Russian soldiers died when a mine blew up their armored vehicle Saturday near Bachi-Yurt, 40 km (25 miles) east of Grozny.
Rebel leaders agreed last week not to resume all-out warfare in response to the Russian onslaught, but radical field commanders have threatened to make strikes outside Chechnya.
The rebels have already made two bloody hostage-taking raids outside Chechnya since the conflict started. One aim of further attacks would be to force Moscow into peace talks, although they might also prompt fierce retaliation from Russian troops. (Reuters)