MOSCOW--The Communist Party yesterday opened the possibility of radical change in the Soviet Union's structure by offering new powers to the republics and a possible rewrite of the agreement that united them.

The party leadership tendered the proposal published in its newspaper, Pravda, as its solution to the ethnic conflicts that threaten to rip apart the Soviet Union. More than 200 people have died in ethnic strife in the past 18 months, and groups in several of the 15 republics are calling for secession.

In its proposals, the party offers no specific solutions to stem the ethnic hatred that has led to clashes involving Armenians, Azerbaijanis, Abkhazians, Georgians, Turks, Uzbeks and others. Some activists welcomed the party's attempt to compromise, but said vague promises of decentralization are no longer enough to solve "the nationalities question."

"The only solution is for the republics to be absolutely free," said Nodar Notadze, head of the People's Front in Georgia.

The draft policy also calls for a law banning "nationalist and chauvinist" organizations, which could be used against groups demanding independence from Moscow.

The greatest concession offers the republics the power to question national laws before a strengthened high court.

That clause appeared to be aimed at Estonia, Latvia and Lithuania, which have amended their constitutions to proclaim their right to reject national laws. The Kremlin previously said this violated the Soviet Constitution.

Yesterday's document said that to achieve a transformation of the Soviet federation, "the question has been raised of working out and signing a new union agreement instead of the Treaty on the Formation of the U.S.S.R. of 1922."

That could be limited to the party's suggestion of expanded powers for republics. But it opens the possibility that radicals could push through radical change such as Andrei D. Sakharov's suggested loose confederation of sovereign states, or even the breakup of the union into independent states.

The 1922 treaty created the U.S.S.R. as a union of allegedly sovereign republics which were in reality dominated by the Kremlin in Moscow.

Estonian activists originally suggested rewriting the treaty of union in November, when they made world headlines by becoming the first of the Baltics to declare their republic "sovereign" within the framework of the Soviet Union.

By yesterday, however, Baltic activists were no longer excited by the possibility.

"We don't want a new agreement," said Aigar Irgens, an editor at Atmoda, the newspaper of the Latvian Popular Front. "We want complete independence."

"They are trying to present to the world that we in the Soviet Union now have a federation built on the will of the people," said Alvydas Juozaitis of the Lithuanian popular front, Sajudis. That is impossible as long as the Red Army "occupies" the republic, he said.

Sajudis, which swept parliamentary elections in Lithuania in the spring and openly advocates independence, is "not prepared to sign a new agreement with the Soviet Union until the Soviet Union renounces our occupation," Juozaitis said.