Gorbachev, Foe Confront Economy : Soviet Union: A committee formed with Yeltsin signals the leader’s willingness to move faster toward market reforms.

President Mikhail S. Gorbachev and his main political rival, Boris N. Yeltsin, have formed a joint committee to revamp the Soviet economy, a sign that Gorbachev is willing to move faster toward market reforms.

The 12-member committee, which held its first meeting today, brought together moderate reformers loyal to Gorbachev and more radical reformers supporting Yeltsin, the president of the huge Russian republic who recently quit Gorbachev’s Communist Party.

A Western diplomat termed the move “rather important” because the national government was in danger of falling far behind economic changes introduced in Russia, the largest of the Soviet Union’s 15 republics.

“If they don’t do something like this, they are going to be left behind,” the diplomat said, speaking on condition of anonymity. “Russia is going to move ahead fast.”

More rapid reform of the Soviet economy could also increase the chances for obtaining Western aid, which Gorbachev says is necessary to reform the economy.

Gorbachev’s top economic adviser, Nikolai Y. Petrakov, said in an interview that the decision to form the committee was “the most important information of 1990” in Soviet domestic politics. He said Gorbachev and Yeltsin signed the agreement Saturday after several days of talks.

The economists appointed to it will develop a common economic policy for the nation. Petrakov said it is too early to say what they might recommend, but their work should be done by Sept. 1 when the national and Russian parliaments reconvene. Economic reforms will be of top priority at the sessions.

The committee includes such proponents of reform as Petrakov, Deputy Premier Leonid A. Abalkin, Presidential Council member Stanislav Shatalin, economist and writer Nikolai Shmelev, Yeltsin deputy Grigory Yavlinsky and Russian Finance Minister Boris Fyodorov.

The Interfax news service identified Yavlinsky as the author of Yeltsin’s “500 Days” economic program to move Russia to a market economy.

Over Gorbachev’s objections, Yeltsin was elected in May to head Russia, which contains three-fourths of the Soviet Union’s land and more than half its people. Since then, he has slowly outlined plans to overhaul the republic’s economy.

He has shown tolerance toward private property and in recent weeks indicated he intends to radically reform land ownership and seize control of banking. That brought a sharp response from Gorbachev, who on Sunday urged Soviet republics not to try to break away from the central money and banking system.

Gorbachev and his premier, Nikolai I. Ryzhkov, have moved more slowly on the economy and are facing sharp criticism for its failures. Yeltsin and other reformers have urged Ryzhkov to resign. Yeltsin also quit the Communist Party last month, starting an exodus of leading reformers.