President Boris Yeltsin on Thursday extended his ultimatum for Chechen fighters to lay down their arms until Saturday midnight and appealed to President Dzhokhar Dudayev to resume talks, in the first hint of reconciliation since Russian troops poured into the breakaway republic.


Yeltsin's statement said attempts by Russian forces to "guarantee the security, constitutional rights and freedoms of citizens" were continuing to be met by violence.


"Striving to reduce to a minimum the use of force, which could unfortunately lead to casualties among the civilian population, the period for voluntary laying down of arms and the cessation of hostilities against the federal forces of law and order is extended for 48 hours, beginning from 00 hours on Dec. 16," said the statement which was circulated to news organizations and read out on national television.


The move, which came as Russian forces in Chechnya advancing from the west, north and east continued to tighten their grip on Grozny, appeared to provide both sides with a chance for compromise after a steady build-up of confrontation.


It would also give Russian troops extra time to consolidate their positions around the capital after a series of holdups and delays.


"The best way out of the complex situation would be to cease fire and sit down at the negotiating table without any kind of preconditions," Yeltsin said. "If Dzhokhar Dudayev agrees personally to head the Chechen delegation to the talks, I will send a fully empowered, high-level Russian delegation." Dudayev was quoted late Thursday by Interfax as describing Yeltsin's proposal as "a step in the right direction, showing evidence of a healthy approach." Earlier in the day Dudayev had himself called for new talks, without preconditions, state television reported.


A letter signed by the Chechen foreign minister, Shamsedin Yusef, asked for a meeting with U.S. Vice President Al Gore to discuss ways of ending the crisis, Reuters reported. Gore is currently visiting Moscow, where he has reiterated the American position that Chechnya is a Russian internal affair.


Yeltsin concluded his statement by expressing his conviction that "peace and calm will soon triumph in the Chechen republic."


But there was scant indication of this happening in Chechnya, as Russian tanks and infantry took up positions in the hills above Grozny. Heavy shelling, which died out late Wednesday night, resumed at 5 A.M. Thursday.


No casualty figures were available from the Chechen side, but hospitals in Grozny said they were treating wounded from the village of Pervomaiskoye, 14 kilometers to the northwest of the capital, as well as the bodies of a whole family whose house had taken a direct hit.


In Moscow, Viktor Ilyukhin, who heads the security committee in the State Duma, quoted the Defense Ministry as saying 15 Russians had been killed in fighting so far, according to Reuters. Russian television broadcasts have put that figure at closer to 70.


A proposal to devote the Duma agenda for the day to a discussion of events in Chechnya was rejected, as was an emotional appeal from liberal legislator Ella Pamfilova for the entire Duma immediately to cease its work and fly en masse to Grozny.


The shelling around the Chechen capital eased during the middle of the day as a heavy fog descended on the region, but resumed again later near Chechen positions around Pervomaiskoye.


On the main road north from Grozny, a city of 400,000 in peacetime, Chechen soldiers were busy digging trenches with an excavator and pushing concrete blocks across the road with an armored personnel carrier.


Itar-Tass reported that some Russian units had already reached the outskirts of Grozny from the north and west and that the operation to seal off the city was expected to be completed by the end of the day. It said the southern side of the city was still left open to allow alleged mercenaries from foreign states to leave.


However, Reuters reported eyewitnesses saying that a third column of tanks remained about 45 kilometers west of Grozny early Thursday.


Except for Yeltsin's announcement, all indications have been that Russia was intent on military action.


The Russian negotiating team which had been holding talks with a Chechen delegation in Vladikavkaz said it was returning home, after the Chechens walked out of the talks Wednesday.


Itar-Tass said Thursday that the government has sent a formal note to embassies in Moscow warning foreigners against traveling to Chechnya because it cannot guarantee their safety.


Foreign Minister Andrei Kozyrev said Russia wanted to end the crisis within the next few days, implying that the scale of the military operation would be stepped up.


He said Moscow still hoped for a peaceful solution of the crisis "but in any event, it will be solved in the next few days," Interfax quoted him as saying.


Chechen Deputy Foreign Minister Ruslan Chimayev, in Moscow to rally support and sympathy for his republic's position, told The Moscow Times on Thursday he saw little chance of a peaceful outcome.


"The Russian forces cannot withdraw now, because if they leave, many members of the party of war will have to resign," he said.