The Soviet Union is selling few, if any, products to the United States that are made by slave labor, the International Trade Commission said yesterday in a report that the Reagan administration is counting on to defuse a campaign by its conservative allies to ban imports of Soviet goods.

"The ITC report suggests that the United States is not importing large quantities of goods made by convict labor" from either the Soviet Union or China, said Sen. Robert J. Dole (R-Kan.), who requested the ITC study.

But it appeared unlikely that the report would end the year-long dispute, in which the administration was caught between its conservative allies who want strict bans on U.S. imports of Soviet products made with slave labor and the president's own desire to open new arms control and trade talks with Moscow.

Conservative groups pressing for the ban on imports said yesterday they would continue their fight, including a suit by the Washington Legal Foundation to force the administration to impose import bans under a rarely applied 54-year-old law.

Foundation attorney Paul D. Kamenar, noting that Customs Commissioner William von Raab ruled in September 1983 that as much as $138 million of the Soviets' $227.5 million in exports to this country were made by slave labor, said, "Von Raab made the determination, and the State Department has been trying to frustrate his carrying it out."

"The law's the law," he continued. "The operative determination by Customs has been made, and we are trying to get it enforced."

The Justice Department, in its defense against the foundation suit, contended that no determination on Soviet slave labor had been made by a federal agency, and that none would be until the Treasury Department gets the ITC report.

Treasury Secretary Donald T. Regan originally supported von Raab's plan to apply the forced labor ban against 36 Soviet products, but backed off after being told of its repercussions by Secretary of State George P. Shultz, Commerce Secretary Malcolm Baldrige, Agriculture Secretary John R. Block and U.S. Trade Representative William E. Brock.

The ITC disputed the original figures of Customs, which has since lowered its number substantially. The ITC said the value of goods made by slave labor exported to the United States would at most range from the new Customs estimate of $10.9 million to one by the Commerce Department of $27.6 million.

The major product in both estimates, however, is refined petroleum products, in which labor amounts to as little as 2 percent of the production costs.

"With labor comprising such a small part of the total," the ITC said, "the amount of compulsory labor used rather than regular labor may be negligible."

The ITC also found little likelihood that products made by forced labor in 22 other nations, including China and South Africa, were being exported to the United States.

The major export from China to the United States, gasoline, "is believed to involve little or no compulsory labor," the ITC said, although other exported products might use forced labor. As for South Africa, the ITC found no evidence but acknowledged "a potential" for American imports of farm products and precious metals to be produced or mined with slave labor.

The issue of Soviet use of slave labor for export products emerged in 1982 with allegations that forced labor was used to build the pipeline from Siberia carrying natural gas for sale to Western Europe. The administration, however, has softened its stance since a February 1983 report in which the State Department said the Soviet Union operates the world's largest "forced labor system," with an estimated 4 million workers in 1,100 camps.

A year ago, administration witnesses stressed to Congress that there was little "specific evidence" of the Soviet use of slave labor on exports. CIA Director William J. Casey reported last May that an intelligence search failed to develop information "sufficiently precise to allow us to determine whether and to what extent the products of forced labor are exported to the United States."