The leaders of France and Germany called today for an urgent meeting of representatives from the world's seven leading industrial democracies and Russia to assess whether Yugoslav President Slobodan Milosevic is prepared to accept their conditions to halt NATO's bombing campaign.

French President Jacques Chirac and German Chancellor Gerhard Schroeder said Belgrade appeared to have taken a step toward peace by announcing it was ready to embrace the principles laid down by the Group of Eight nations.

But senior NATO officials expressed skepticism about any breakthrough, noting that Milosevic had steadfastly refused to drop objections to NATO's key demand that an international peacekeeping force sent to Kosovo include a substantial core of NATO soldiers and operate under allied command.

The official Yugoslav news agency Tanjug reported late Friday after nine hours of discussion between Milosevic and Russia's special envoy, Viktor Chernomyrdin, that the Belgrade government was willing to embrace "the general principles" of the G-8 countries as the basis for a peace settlement.

These conditions include an end to violence and repression in the southern Serbian province, the withdrawal of Yugoslav forces, the introduction of an effective international security presence, the creation of an interim administration and safe passage for refugees back to their homes.

But Western leaders reacted cautiously to the reports of Belgrade's concession, saying that Milosevic's proven record of broken promises did not inspire trust. When asked if Milosevic had any maneuvering room in negotiating an end to the bombing, Chirac said flatly, "No, he doesn't have any."

"Before we can know whether this is real progress, we must first find out whether Milosevic will accept a credible military force with a NATO core to escort the refugees home," said British Foreign Minister Robin Cook in London.

Chirac met Schroeder in the southern French town of Toulouse to discuss Kosovo and the timetable of international summitry that might influence the diplomatic course for a resolution to the crisis. The European Union will meet next week in Cologne, Germany, to be followed in the same city by a conference of foreign ministers from G-8 countries and a gathering of government leaders from the same nations June 18-20.

NATO military commanders have warned that unless diplomacy or pressure from the bombing campaign changes the situation in the coming weeks, allied leaders might need to consider deploying up to 150,000 ground troops. Those troops would have to make a forced entry into Kosovo if NATO is determined to get the nearly 1 million ethnic Albanian refugees home before winter.

To assist ethnic Albanians still trapped inside Kosovo, a New York-based relief organization, the International Rescue Committee, is to begin airdropping supplies to the Serbian province Monday, the Associated Press reported. Moldovan pilots in private planes will fly the missions.

Pentagon officials wished the effort success but said the pilots will be at great risk because NATO will not patrol the route.

Senior U.S. and NATO officials have expressed grave doubts about Chernomyrdin's peace mission because Russia has been reluctant to endorse NATO's determination to play the leading role in a peacekeeping force. The alliance insists that its troops, including those from the United States and Britain, must assume control of the operation to reassure the refugees that they will be protected.

Russian Foreign Minister Igor Ivanov acknowledged today that Moscow's diplomacy was encountering trouble, and he complained that Western nations did not appreciate Moscow's peacemaking efforts. "I will put it straight," he said, "The situation is not easy at all. To be even more exact, it is hard. The efforts which are being made by Russia, and in particular by the president's envoy Viktor Chernomyrdin, do not find any understanding or necessary support of NATO's leadership."

Ivanov told reporters that a U.N. tribunal's indictment of Milosevic and three other Yugoslav officials on war crimes charges "has made the whole process of finding a settlement in Kosovo much more difficult. No one doubts today that the conclusions drawn were, to say the least, hasty, and this decision politicized."

Chernomyrdin said after his talks with Milosevic that he was "very pleased" with the outcome, but there was no official word upon his return to Moscow about what he had achieved. Chernomyrdin said he believed he had made enough progress to return to Belgrade next week.

Chernomyrdin was reported to have discussed a complete peace proposal with Milosevic that won his approval. The Russian Tass news agency said the terms of the proposal called for a U.N. peacekeeping force in Kosovo under the command of an officer from a neutral country. While some NATO troops might be permitted inside the province, forces from those countries that conducted airstrikes would be deployed only outside Yugoslavia and restricted to the role of disarming the Kosovo Liberation Army -- the ethnic Albanian guerrillas who are fighting for an independent Kosovo.

While reaffirming NATO's will to do everything possible to get the refugees back home with peace and security, Deputy Secretary of State Strobe Talbott -- who has been holding intensive talks with Chernomyrdin about the outline of a settlement -- said NATO would insist on keeping the unity of command and playing a core role but would not require its name on the peacekeeping force. But when asked if the countries leading the airstrikes, such as the United States and Britain, could be excluded from being present on the ground in Kosovo, Talbott replied, "Forget it."

While the diplomatic maneuvering continued, NATO launched some of the most ferocious airstrikes of the campaign soon after Chernomyrdin left Belgrade late Friday, plunging the capital and other major cities into darkness as more power stations were knocked out.

"For the fourth consecutive day, we flew well over 600 sorties, flying 218 specific strike missions and another 78 strike sorties designed to suppress Serb air defenses," said NATO spokesman Peter Daniel.

[NATO bombing raids today killed four people and injured about 30, the official Yugoslav news agency Tanjug said. The bombs also wrecked the center of Cuprija, the agency reported, destroying or damaging about 100 residential and commercial buildings. Cuprija is about 65 miles south of Belgrade.

[The agency said two people were killed and 11 injured when NATO missiles crashed into Camurlija, a village northwest of Nis, Serbia's third-largest city. Two people were killed when bombs struck the Cenovacki bridge over the Jablanica River in southeastern Serbia, Tanjug said.

[Local media said NATO also struck hard early Sunday at Belgrade and other key cities of Serbia and Kosovo, targeting communications, transport and defense systems.]

NATO officials pointed to further reports of dissent within the Yugoslav army. Military authorities were reported to have arrested 24 army reservists in the southern town of Krusevac after anti-war protests and warned that those who fail to report for duty will suffer serious consequences, as will their families.

Correspondent David Hoffman in Moscow contributed to this report.