MOSCOW (AP) _ The vast Russian republic proclaimed its sovereignty today with a declaration that signaled a sharp break with the central Soviet government but carried no legal force.

Deputies of the Russian Congress, who overwhelmingly approved the declaration, stressed the move does not amount to a declaration of independence like that of the breakaway Baltic republic of Lithuania.

''We didn't declare ourselves a separate government from the U.S.S.R.,'' said Ruslan Khasbulatov, the Congress' deputy chairman. ''We think our Russian fate should be within the framework of the U.S.S.R.''

The lawmakers last month elected as the republic's president Boris N. Yeltsin, the populist reformer who backs a more radical shift to a market economy than Soviet President Mikhail S. Gorbachev.

There was no immediate reaction by Gorbachev, who has warned that the Kremlin cannot carry out its reforms if the Russian heartland is not firmly behind it.

Yeltsin had urged quick passage of the measure so that June 12 could become ''Russia's independence day.'' The vote was 907-13, and the result was met with applause and a standing ovation. Yeltsin stood and applauded the deputies.

Earlier in the day, deputies voted 704-206 not to drop the ''Soviet Socialist'' from the republic's formal name: The Russian Soviet Federated Socialist Republic.

Today's declaration does not actually have any effect on the laws of Russia, by far the largest of the country's 15 republics, comprising two- thirds of the country's territory and just over half its population. The declaration is, however, the basis for writing a new Russian constitution.

Passing a declaration that carried legal force, Khasbulatov said, ''would have called forth a big crash.''

The declaration ''solemnly proclaims the state sovereignty of the Russian Soviet Federated Socialist Republic on all its territory'' and says laws of the Russian Federation should have priority over centrally dictated Soviet laws.

The declaration says the republic has the right to secede from the Soviet Union under conditions to be stated in a future nationwide treaty. But the proclamation serves only as a political statement of intent, with no legal weight.

Still, it ''expresses the mood of decentralization in the country,'' said Vyacheslav Maslennikov, a consultant for the Congress' editorial commission.

The Russian action falls far short of secessionist drives in the Baltic republics of Lithuania, Estonia and Latvia.

The three Baltic presidents formed a united front last month to press their drives to restore the independence they lost 50 years ago when forcibly annexed.

Lithuania has gone the farthest toward secession by declaring its immediate independence on March 11.

A radical Russian deputy, Mikhail Maley, said his wing ''had a great desire to pass a real declaration'' of sovereignty, but conceded that lawmakers would not have accepted such a move.

Yeltsin, elected to the republic's presidency last month, has been a strong proponent of Russian sovereignty. He included it in his platform and predicted it would be declared in the first 100 days of his tenure.

''I think it has great political significance for our government,'' Khasbulatov, a strong supporter of Yeltsin, said of the declaration. ''It's an extraordinary event for our country, for our Russia.''

Eventually, he said, Russia would ''go on our own ideas,'' especially in the area of economic reform. He said the Russian government hoped to take control of its own foreign trade.

Yeltsin, who has become Gorbachev's political nemesis in the last two years, has said he hopes to cooperate with the Soviet president despite their personal and political differences, but that his first priority is defending Russia's interests.

Gorbachev, who had opposed Yeltsin's election as president of the Russian republic, indicated last week he would seek a reconciliation with him.

''What would disturb me more than anything at this stage is a split in the democratic forces,'' he said. That implied that he viewed Yeltsin as an ally in the reform movement.