MOSCOW -- The Russian Orthodox Church chose a new patriarch, Alexii of Leningrad, in a compromise Thursday between the conservative-minded hierarchy and reformers who favor a separation between church and state.

The Soviet news agency Tass said that Alexii, 61, was elected in a secret ballot conducted among more than 300 members of the church synod meeting in the monastery of Zagorsk, north of Moscow. Alexii succeeds Patriarch Pimen, widely regarded as a stooge of the communist authorities, who died May 3 after 19 years in office.

Alexii, who is of Baltic descent, was one of three candidates nominated by a council of bishops for the post of patriarch of the 50 million-member church. He defeated the ultraconservative Filaret of Kiev, the acting patriarch many observers had considered the most likely successor to Pimen.

The election of Alexii is the first contested election of a Russian Orthodox patriarch in Soviet history. It is also the first time that the acting patriarch has not automatically succeeded his predecessor.

Alexii, who ran the Diocese of Estonia as well as the Diocese of Leningrad, is regarded as a capable administrator who will present no serious problems to the communist authorities. He is a more ecumenical candidate than Filaret, who compromised himself by his vehement opposition to the legalization of the Ukrainian Catholic Church.

Since Mikhail Gorbachev came to power in 1985, the Russian Orthodox Church has generally taken a much more conservative stand than the Communist Party leadership on many religious issues. Earlier this week, Filaret told a Soviet newspaper that the church was not ready for radical change.

The Orthodox Church has been allowed to reopen many parishes under Gorbachev. But church leaders have been reluctant to take advantage of the more liberal climate.

A dissident Orthodox priest, Gleb Yakunin, said in an interview this week that all the official candidates had been tarred by collaboration with the authorities during the Brezhnev period. He predicted that there would be little change in the church under Alexii.

"The church is organized like the army. Ordinary priests are afraid to express their opinion because they fear they would be punished. If you step out of line, you can be sent off to a far-off parish and never heard from again," he said.

During his campaign last year for membership in the Soviet congress of people's deputies, Alexii promised to do something about ecological problems in Estonia. But he has made little impact as a member of the Soviet legislature.

The third candidate in Thursday's election was metropolitan Vladimir of Rostov. Vladimir was favored by the reformers largely because he had spent less time in high office than either Alexii or Filaret and was therefore less tainted by charges of collaboration.