MOSCOW, JUNE 13 -- Lithuanian Prime Minister Kazimiera Prunskiene said today that the Kremlin has agreed to relax economic sanctions against her separatist Baltic republic and that both sides in the dispute were headed toward a negotiated resolution of the Soviet secession crisis.

Following a meeting here today with Soviet Prime Minister Nikolai Ryzhkov, Prunskiene said she had received assurances that Moscow would resume some deliveries of natural gas to factories in Lithuania. Moscow's seven-week-long embargo on fuel supplies and raw materials has shut down Lithuanian power plants and industries and has put tens of thousands of people out of work.

A Lithuanian official said Ryzhkov had agreed to increase natural gas shipments by 15 percent, bringing the republic up to about 30 percent of its normal supply. The Soviet news agency Tass said that supplies of some raw materials also are being restored, but a Lithuanian spokeswoman said she had no information on such deliveries.

Tass quoted Prunskiene as saying after meeting Ryzhkov, "We have no doubts the economic blockade will be lifted." Prunskiene said that Soviet leader Mikhail Gorbachev's meeting Tuesday with the presidents of Lithuania, Latvia and Estonia had been a success and that the two sides appear to have found a formula to begin negotiations on a transition to full sovereignty for the Baltics.

The Kremlin had insisted for weeks that the three Baltic republics -- forcibly incorporated into the Soviet Union in 1940 -- repeal their declarations of independence from Moscow before discussions could start, but they refused. In a speech to the Soviet legislature Tuesday, however, Gorbachev declared that Lithuania had merely to suspend laws it passed to implement the March 11 independence declaration for a dialogue to begin.

The three republics will probably suspend those laws during the negotiations with Moscow, sources said, while Moscow would lift the Lithuanian embargo entirely for the same period.

Tass quoted Ryzhkov as describing today's encounter with Prunskiene as "the beginning of a concrete dialogue on the question of future negotiations." And Prunskiene, in an interview with Radio Moscow, said, "The Soviet government has begun to trust us more, and we have begun to trust it more. We have no doubt that it is ready to end the sanctions. This was said concretely, so we now have the chance to act and open contacts with the Soviet government."

Although Soviet law requires a period of up to five years before secession of one of its republics is allowed, Prunskiene told the Estonian media that she thought a negotiating period of about two or three months would be enough to work out the difficult problems of political authority and property. Ryzhkov said he thought the negotiating period would last two or three years.

President Bush told reporters in Washington that he applauded the "significant change" in Gorbachev's relations with the Baltic leaders. Bush said he hoped that Gorbachev's and Ryzhkov's meetings with the three Baltic presidents marked a "first step in a dialogue that will lead to the self-determination that we strongly support."

Radio Moscow said Gorbachev did not attend today's meeting with Prunskiene because he was not feeling well. Although there were no details available on Gorbachev's health, he looked exhausted during a speech to the legislature earlier this week and paused repeatedly to cough.

Prunskiene, as well as the Baltic presidents, showed enthusiasm for Gorbachev's new plan to transform the country into a "union of sovereign socialist states." The Baltic leaders, however, seemed not so much interested in joining such a union permanently but rather pleased that Gorbachev was serious about coping with independence movements throughout the country.

During a meeting Tuesday of the Federation Council, a presidential advisory body that includes the presidents of all 15 Soviet republics, Gorbachev proposed a new state structure that he said would decentralize power and create a system of political and economic treaties and agreements between and among the republics.

The independence movements in the Baltics and other Soviet republics, as well as the recent adoption of a decree on sovereignty in the vast and powerful Russian republic, appears to have forced Gorbachev to move more quickly than he may have wished.

"We used to talk about the renewal of the present union, but now we are talking about a completely new union," said Gorbachev's press secretary, Arkady Maslennikov. "The situation is no longer like it was five years ago, or even one year ago. The pace of events has overtaken us."

A new treaty of the union, worked out on a "cooperative decision-making process," would make Moscow responsible mainly for the conduct of foreign and defense policy and some central financial functions.

At the council meeting, Gorbachev and his longtime political rival, Boris Yeltsin, the newly elected president of the Russian republic, seemed to improve their personal relations and to agree on the need for such a new form of federation.

"We shook hands and we met each other halfway," a smiling Yeltsin told a session of the Russian legislature today. "We will be cooperating on a reciprocal, businesslike basis, and we agreed that Russia cannot exist without the entire country, and the country cannot exist without Russia." Yeltsin said he had no interest in the collapse of the union.

"Whether we call the new form a federation or a confederation is not important," he said. "The point is that it represents a democratization of our national relations."

Gorbachev told the presidents of the 15 republics that new relations with Moscow and among the republics themselves would depend "on the mutual interest of the parties involved" rather than on the unilateral demands of the Kremlin. Since 1922, the country has technically been a voluntary union of republics, but, as Maslennikov said, "this was not our reality."

A resolution of the Baltic independence struggle also could lead to U.S. congressional approval of a trade pact signed during the Washington summit two weeks ago. Lawmakers have said they would not approve the pact unless Gorbachev opens negotiations and lifts the embargo against Lithuania.

The pact is important because it could clear the way for the United States to grant most-favored-nation trade status to the Soviet Union, a benefit that could help Gorbachev in his effort to improve the dismal state of the nation's economy.