A Soviet trade official said today that American companies are not being considered for long-term development projects here because of a history of unstable trade relations with the United States.

"To have long-term 'turnkey' projects, there should be a good long-term relationship," said Gennady Zhuravlev, first deputy minister for foreign trade. "Such is not the case with the United States."

In the last year, the Soviets have turned increasingly to "turnkey" projects with foreign firms, giving them control of construction from design to finish.

At a press conference today to announce 1984 Soviet foreign trade figures, Zhuravlev accused the United States of discriminating against the Soviet Union by withholding "most favored nation" status on tariffs and by imposing controls on high-technology exports.

Soviets officials also have argued that a series of U.S.-imposed trade embargoes and sanctions, initiated after the 1979 Soviet invasion of Afghanistan and again after the adoption of martial law in Poland, have made dealing with American firms a risky business.

The Soviets are said to be closely following progress of the export administration act in Congress, which contains a "contract sanctity" provision barring the government from interrupting existing trade agreements except in the case of war.

According to some western diplomatic and business sources, American firms have been invited to bid on subcontracts for projects in the next five-year plan, although in many cases the prime contractors are western European or Japanese-headed firms or multinational consortia.

Zhuravlev did note, however, that "some shifts" in American attitudes could lead to an improvement in trade relations between the two countries.

He noted in particular the arrival of U.S. Secretary of Commerce Malcom Baldrige in Moscow next month to meet with his Soviet counterpart, Foreign Trade Minister Nicolai Patolichev. It will be the first meeting of the Joint Commercial Commission since 1978, two years before the U.S. embargo on grain exports to the Soviet Union imposed in the wake of the Afghanistan invasion.

That embargo was lifted in 1981 by President Reagan, and last year, near-record U.S. grain sales to the Soviet Union boosted overall U.S.-Soviet trade 64 percent since 1983.

The increase puts the U.S. in fifth place among the Soviet Union's capitalist trading partners, outranking Japan. The U.S. grain imports, bought to cover last year's disappointing Soviet harvest, were estimated at $2.8 billion.

The jump in agricultural sales more than covered the decline in nonagricultural U.S. imports and a 10 percent drop in Soviet exports to the United States.

Overall, U.S. trade with the Soviet Union went from $1.9 billion (1.8 billion rubles) to $3.27 billion (3.1 billion rubles), by far the largest increase of any country.

The 1984 figures have shown that, for the first time in many years, the Soviet Union last year showed a modest trade surplus, although the sum was not revealed. According to western observers, the surplus was largely because of a drop in nonagricultural western imports.

The 1984 figures, for instance, show a net drop in imports from Italy, Finland and Japan.

The figures also showed the continued improvement in trade relations between the Soviet Union and the People's Republic of China, a trend noted prominently today by Zhuravlev. Turnover between the two countries went from 223 million rubles ($257 million) in 1982 to 977 million rubles ($1.12 billion) in 1984.

Soviet exports to Nicaragua more than tripled between 1983 and 1984, from 42.4 million rubles to 137.6 million rubles.

A foreign trade ministry official today explained that Soviet imports of oil from Saudi Arabia had increased to cover obligations incurred by Iraq.