The Roman Catholic and Russian Orthodox churches will open talks next month on the status of the long-suppressed Ukrainian Catholic Church in an apparent bid by the Soviet Union to establish relations with the Vatican.

Orthodox Metropolitan Filaret of Kiev said Saturday that the two delegations would meet next month at a monastery in Finland for their preliminary discussions of the religiously and politically sensitive issue.Filaret, whose archdiocese is headquartered in the Ukrainian capital of Kiev, said that the talks would not be negotiations but attempts to clarify the positions of the two churches on the Ukrainian Catholic Church, whose members' allegiance is to Rome.

For Catholics, the only acceptable resolution would be legal status for the Ukrainian, or Uniate, church after four decades of state persecution and an underground existence.

Filaret, speaking to reporters at the Danilov Monastery here, acknowledged the strong desire of the Russian Orthodox Church and of the Soviet government to improve relations with the Vatican as they observe the millenium of Christianity in Russia.

That meant, he acknowledged, discussing - if not resolving - the status of the Ukrainian, or Uniate, church, which was outlawed by Soviet dictator Josef Stalin in 1946 when he ordered its merger with the Russian Orthodox Church.

If the Vatican became "aggressive" about the issue, Filaret warned, then the dialogue would be difficult.

The issue is complex, intertwining theological and ecclesiastical disputes going back centuries with Ukrainian nationalism, resistance to Soviet rule and socialism, and the alleged collaboration by church members with the Nazi occupation of the Ukraine in World War II.

Calling the Uniate church "traitorous," Stalin outlawed it immediately after the war, as the Soviets put down an upsurge of nationalism in the Ukraine.

Since then, a whole hierarchy of Uniate bishops, priests and nuns have ministered to a congregation estimated at 3 million to 4 million at secret Masses held in private apartments, remote farmhouses or deep in the forests of the Ukraine.