President Mikhail S. Gorbachev Tuesday rejected exiled writer Alexander Solzhenitsyn's recent proposals for replacing the Soviet Union with an all-Slavic state as disrespectful to other ethnic groups.

In his first public remarks on Solzhenitsyn's suggestions, the 59-year-old Soviet leader said they were unacceptable and sharply conflicted with his own views on how to restructure relations among the 15 Soviet republics."As a politician, his views on the future of our multinational state are unacceptable," Gorbachev told the Supreme Soviet legislature. "They are far from reality. These views have a destructive character."

Gorbachev's remarks put him into a competition with Solzhenitsyn, a Nobel laureate, for the hearts and minds of the Russian people and underscored the writer's increasing importance.

In his article, which appeared Sept. 18 in the reformist newspaper Komsomolskaya Pravda, Solzhenitsyn, 71, called for spirituality over materialism and a unified Slavic nation. He criticized Gorbachev's reforms.

Solzhenitsyn suggested forming a "Russian Union," which would include the republics of Russia, Byelorussia and the Ukraine. A large part of Kazakhstan would also be included. The other 12 Soviet republics, including the rest of Kazakhstan, have different cultures and should be allowed to secede, he said.

It was the first piece he has written directly for the Russian people since he was exiled and stripped of his citizenship in 1974.