KIEV, U.S.S.R., OCT. 28 -- The principal opposition movement in the Ukraine today called for complete independence from Moscow, a move that if successful could lead to an eventual breakup of the Soviet Union.

Meeting in a Kiev cultural center, the 2,300 delegates to the second congress of the opposition group Rukh voted by an overwhelming majority to call for "the renewal, by nonviolent means, of the state independence of the Ukraine." The delegates also deleted references from the group's founding charter explicitly supporting President Mikhail Gorbachev's perestroika reform movement.

Rukh's decision to push for the establishment of an independent Ukrainian state reflects the radicalization in the political life of the Soviet Union's second-largest republic over the past two years. Once regarded as a conservative stronghold under the tight control of the Communist Party, the Ukraine now appears to be following the Baltic states down the path to secession.

The Ukraine, which for most of its history has been part of other European empires, enjoyed limited independence immediately after the 1917 Bolshevik Revolution before being incorporated into the Soviet Union in 1922 at the end of its civil war.

In calling for full independence, Rukh, which controls one-third of the seats in the Ukrainian assembly, discarded its original goal of sovereignty for the Ukraine within a reformed Soviet confederation.

Disillusioned by the slow pace of economic change in the Soviet Union, Rukh leaders have concluded that the Ukraine has no choice but to go it alone to extricate itself from the nation's growing economic crisis. As a preliminary step to independence, Rukh is calling for the creation of an independent currency and the erection of customs barriers to allow the republic to carry out its own economic reforms.

"We have understood that the only way out of our crisis is also the way out of the Soviet Union," said Volodymyr Cherniak, a Rukh vice chairman. "A sovereign, independent Ukraine will have the chance to solve its own problems.

"In the long run, I do not think that the Ukraine can be self-sustaining as a state. We will have to have relations with Russia. But they will be relations of two independent states. The way to integration is through disintegration," Cherniak said.

Although the Kremlin has so far refused to allow a break by any of the three Baltic states and has not yet begun formal negotiations with them on their demands, most Rukh leaders expect the road to independence to be even longer and more arduous for the Ukraine. Ukrainian independence is opposed not merely by the authorities in Moscow, but also by a wide spectrum of the ethnic Russian public, from hard-line Communists to right-wing nationalists to liberals.

Unlike the Baltic states, which were incorporated into the Soviet Union in 1940, the Ukraine has long been regarded by most Russians as an integral part of a great Slavic homeland. The republic -- which has a population of 52 million, or about 20 percent of the total Soviet population -- provides the Soviet Union with 25 percent of its food and coal and 20 percent of its gross industrial output.

Many Russians regard Kiev as the cradle of "Holy Rus," the predecessor of the modern Russian state, and refer to Ukrainians as "Little Russians." In a recent political pamphlet, exiled Russian writer Alexander Solzhenitsyn accepted the idea that the Baltic states and Central Asia would be lost, but called for the creation of a "Russian Union" made up of Russia itself, the Ukraine and Byelorussia.

"To lose the Ukraine would be like cutting off a limb for many Russians. It's very difficult for them to accept psychologically," said Oles Donij, a student leader and hunger-strike organizer who was elected to Rukh's governing board.

Until the first Rukh congress in February 1989, Ukrainian nationalist sentiment was largely confined to the Catholic western Ukraine, which was annexed from Poland at the beginning of World War II. The Ukrainian national resurgence has now reached Kiev, the republic's capital, and shows some signs of penetrating into the Ukraine's heavily Russified eastern regions.

The interval between the first and second Rukh congresses seems more like an eternity than a single year," said Volodymyr Yavorivsky, a founding member of Rukh and a leading Ukrainian writer. "There's a completely different situation in the republic now -- largely due to Rukh itself. We have become a real political opposition in our parliament."

The blue-and-yellow Ukrainian national flag, officially banned at the time of Rukh's inaugural congress, can now be seen all over Kiev. Much of Rukh's initial program, including a declaration of Ukrainian sovereignty adopted by the assembly in July and the passage of a law making Ukrainian the republic's official language, has been endorsed by the Communist authorities in an attempt to retain some authority.

Earlier this month, the Communist authorities bowed to demands from student hunger strikers for the dismissal of the prime minister and a referendum on whether there should be early multi-party elections for a new assembly. It is conceivable that the Communists, who won a majority of seats during elections earlier this year, will be forced into opposition.

There are disagreements within Rukh over how to promote the goal of Ukrainian independence. The movement's president, Ivan Drach, who was elected to a second term at this week's congress, insists on using only legislative methods. His deputy, Mihailo Horyn, a former political prisoner, said those methods should be supplemented by mass demonstrations and other forms of direct protest.

"With Drach, we will achieve independence in five years. Horyn would like it to take two years," commented a Rukh activist.

Scuffles broke out this morning outside the main cathedral in Kiev, St. Sophia's, when Rukh activists unsuccessfully attempted to prevent the patriarch of the Russian Orthodox Church from conducting a service there. The patriarch was forced to enter the cathedral through the back door after riot police clashed with supporters of the independent Ukrainian Orthodox Church, which was repressed by dictator Joseph Stalin in 1930.

The incident mirrored a similar dispute that occurred in the western Ukraine last year during the campaign to legalize the Ukrainian Catholic Church, which was also banned by Stalin. Many Russian Orthodox churches in the western Ukraine have since been returned to the Catholics.