Small-scale Russian army units have begun probing defenses of the Chechen capital of Grozny in an effort to soften resistance there, bringing ground combat to the besieged and desperate city for the first time in the current offensive.

Russian, Chechen and refugee sources all concurred today that Russian troops had entered the city at various points, but they disagreed about the intensity of the fighting.

Russian reconnaissance units have entered Grozny, the Interfax news agency reported, while other units are digging in in fields to the east. "No major battles are being fought, though there have been sporadic clashes," Interfax reported from Mosdok, the Russian military headquarters in the Caucasus near the Chechen border.

Representatives for the Chechen rebels said Russian troops had begun to storm Grozny. According to an official Chechen Web site, "The storming of the Chechen capital is underway practically at full scale. The outskirts are under uninterrupted attack from virtually all directions."

Fierce clashes took place in the 56th district of Grozny, the neighborhood of Gikalo as well as in Khankala, a town that borders the capital on the southeast and is the site of a military airport, the report said.

Refugees arriving in the neighboring Russian region of Ingushetia from Grozny said Russian artillery has been pounding the city for two days. The southern and western Chernorechnye and Kirova neighborhoods were particularly hard hit, they said. One refugee said he witnessed 12 Russian soldiers trying to fight their way into Minutka plaza, near the city center. The refugee said seven Russians died and the rest retreated.

The action in and around Grozny signals yet again that the Russians want to take it soon, or at least maintain enough pressure so rebel defenders, said to number 2,000, leave. Although Grozny is surrounded, the guerrillas are able to pick their way through static Russian defenses. The probes into Grozny raise the possibility that an all-out battle could coincide with parliamentary elections in Russia scheduled for Sunday.

Russia's plans for capturing Grozny remain a mystery. Officials have talked about loyalist Chechen units invading as a shock force. Before Chechnya's first war for independence, which ended in 1996, Moscow enlisted Chechen fighters to capture the city, and they were repulsed with heavy losses.

Russian officials said 3,000 civilians left Grozny today, but that figure could not be confirmed. The numbers of civilians in Grozny has been a matter of controversy, with Russian officials giving figures as low as 10,00O. With a low number, Moscow could at some point declare the city empty of residents and turn the capital into a free-fire zone. Other population estimates range as high as 40,000.

In Moscow, Emergency Situations Minister Sergei Shoigu said that the two civilian corridors for safe passage out of Grozny would remain open indefinitely--effectively erasing last week's ultimatum, which warned civilians to leave by last Saturday or face annihilation. "Nobody has limited them by any time frame, and nobody intends to limit them," he said.

Shoigu also offered to open talks with Chechen President Aslan Maskhadov about evacuating civilians, but, Russian Prime Minister Vladimir Putin said Maskhadov has no authority in Grozny.

Almost twice as many refugees--2,648--left Ingushetia today to return to their homes in Russian-occupied Chechnya than arrived in Ingushetia in flight from Chechnya. About 200,000 Chechen refugees remain in Ingushetia, which borders Chechnya to the west.

Russia suffered two air losses today: Rebels destroyed a pair of helicopters trying to rescue the pilot of a Su-25 jet downed Monday. The pilot was rescued, but six helicopter crew members died, the Russian Defense Ministry announced.

The air force continued to bomb parts of southern Chechnya, where rebels are gathering to launch attacks.

Correspondent David Hoffman reported from Moscow:

Prime Minister Vladimir Putin, in a blast at Western critics, said Russia will not tolerate "the language of force" from other countries.

In remarks that echoed President Boris Yeltsin's warning to President Clinton last week, Putin said, "We are not used to such language, since Russia has a nuclear shield." On the war in Chechnya, he insisted, "No one can accuse the government of inappropriate use of anti-terrorist measures in Chechnya, or call Russia an aggressor or occupier."

Putin's comments came after he witnessed the ninth test launch of the Topol-M intercontinental ballistic missile, the newest in Russia's arsenal. The three-stage, single-warhead missile is designed to replace aging multiple-warhead missiles that would be banned under the still-unratified START II strategic arms limitation treaty.

CAPTION: A Chechen girl stands near her family's belongings in Shali, near Grozny, as a Russian armored personnel carrier passes by.

CAPTION: A Russian soldier takes aim from a helicopter near Shali, where Russian troops and Chechen rebels fought.