MOSCOW, NOV. 24 -- A senior Soviet official today accused the "right wing" of the American Republican Party and other Washington groups of attempting to undermine the Dec. 7-10 meeting between Soviet leader Mikhail Gorbachev and President Reagan.

"These forces have mounted their own preparations for the summit," Foreign Ministry spokesman Gennadi Gerasimov told a press conference here. He said they have been "issuing all manner of 'reports' and 'studies' rehashing myths of a 'Soviet threat' and palming off provocative falsehoods and rumors to the mass media."

Gerasimov also announced the makeup of the official Soviet summit delegation, which will consist of eight senior Soviet officials. It will be led by Gorbachev and will include Foreign Minister Eduard Shevardnadze and propaganda specialist Alexander Yakovlev, both members of the 13-man ruling Politburo.

Also on the delegation will be Sergei Akhromeyev, chief of the general staff of the Soviet Army; Anatoliy Dobrynin, Central Committee secretary and a former ambassador to the United States; Anatoly Chernayev, a Gorbachev foreign policy aide; Yuri Dubinin, Soviet ambassador to the United States; and Vladimir Kamentsev, deputy chairman of the Council of Ministers.

By including Kamentsev, whose expertise is in trade, the Soviet leadership has signaled an intention of using the talks to boost U.S.-Soviet commercial relations, according to observers here.

Gerasimov's criticism follows a weekend flap over Gorbachev's Washington itinerary, in which suggestions for the Kremlin leader to speak before a joint meeting of Congress were withdrawn because of objections from congressional conservatives.

Blaming the abrupt withdrawal on "anti-Soviet forces," Gerasimov today said, "The sufficiently influential forces opposed to any change for the better in U.S.-Soviet relations have become more visibly active."

Asked to identify the forces he meant, Gerasimov gave as one example the "right wing of the Republican Party."

Gerasimov also referred to U.S. groups that favor improving the U.S.-Soviet dialogue and said that the anti-Soviet influence in the United States was not predominant. He added, "This natural desire for direct communication, for more contacts at the political leadership level, has caused a veritable panic among the ultras attempting to complicate such dialogue in every way."

Noting more positive preparations for Gorbachev's visit -- his first to the United States -- Gerasimov also said that numerous letters have come to the Soviet Embassy in Washington from Americans inviting Gorbachev to visit their towns, farms and homes.

Most Americans, Gerasimov said, "are looking forward to the upcoming Soviet-American summit with approval and hope."

In a separate news conference sponsored here today by the official Novosti press agency, economic officials said they hoped an increase in U.S.-Soviet joint ventures and in Soviet exports to the United States would be two side effects of the summit.

After an intensive year-long effort to form joint ventures between Soviet and western firms, only 15 deals have been concluded, two with American companies.

One reason there have not been more joint ventures with U.S. firms is that the Americans are more interested in marketing their products in the Soviet Union than in investing in companies that would export goods abroad, Vishelov Serov, an official with the Soviet Foreign Trade Ministry, said. He said 20 other Soviet-American business ventures are under discussion.

Vladimir Tschibinov, another Soviet trade official, said the Soviet Union, which exports a limited number of goods to the United States, would like to increase exports such as machine tools, industrial robots and fertilizers.

But the Jackson-Vanik Amendment, which adds tariffs to many goods shipped to the United States from the Soviet Union, makes the cost of exporting such goods prohibitively high, Tschibinov said.