MOSCOW, AUG. 3 -- Soviet President Mikhail Gorbachev and Russian republic President Boris Yeltsin today issued a joint invitation to all Soviet republics to participate in summit talks on creating a new economic reform package.

The invitation to the economic negotiations, which are likely to lead to economic proposals far more radical than the present central government plan, is further evidence of the evolving political cooperation of two political figures who only weeks ago were fierce public rivals.

Gorbachev, who has been able steadily to free himself of the grip of the conservatives in the Communist Party apparatus and has called for a "center-left coalition" to deepen reforms, reportedly has reached agreement in principle with Yeltsin to introduce an unprecedented plan for privatization and denationalization in Soviet industry.

Yeltsin's deputy prime minister, Gennadi Filshin, said Gorbachev is prepared to jettison the central government's more cautious plan for a transfer to a market economy in favor of a far more radical 500-day "transition" program drafted by Yeltsin and his aides in the country's largest and most influential republic.

The invitation to the other Soviet republics is linked to Gorbachev's intention to rewrite the structure of the political arrangements among the 15 constituent republics and Moscow. Gorbachev's decision to draft a new union treaty allowing far greater local control has been forced by the realities of regional politics and demands. With the exception of four Central Asian republics, every republican legislature in the union has issued a declaration either of sovereignty or, in the case of the three Baltic states, outright independence.

Russian republic Prime Minister Ivan Silayev said today that new economic proposals should be prepared by the end of the month. Some republics already have begun meetings on future bilateral economic ties. In Moscow, leaders of the Russian and Lithuanian republics discussed future trade ties today. A spokesman said the Russian republic and Lithuania, which is preparing for independence talks with Moscow, will sign an economic cooperation pact in Vilnius in two weeks.

Gorbachev and Yeltsin already have formed a working group on the new economic program that includes the author of the Russian republic's 500-day program, Grigori Yavlinski, and two members of Gorbachev's inner circle, presidential cabinet member Stanislav Shatalin and economic adviser Nikolai Petrakov. All three have strongly rejected the latest economic reform plan drafted by Prime Minister Nikolai Ryzhkov.