The Soviet Union yesterday finally closed the slander case against two American journalists convicted of libeling Soviet tlevision officials.

The Foreign Ministry told the correspondents, Craig Whitney of the New York Times and Harold Piper of the Baltimore Sun, they deserved to lose their Moscow accreditation, but said it would let them off with a warning in "the interests of developing Soviet - American relations."

At the same time, however, there were mounting indications that the Krelin intends to bring to trial an American businessman, Francis J. Crawford, a representative of International Harvester, on charges of currency speculation.

Yesterday's warning to the two correspondents was the mildest form of reprimand possible.

But the unprecedented libel suit brought by an agency of the Soviet government against the two demonstrated the extent to which the authorities are prepared to go in exerting pressure against unfavorable reporting.

The two journalists, while refusing to participate in the court case against them, had complied with a Moscow judge's order that they pay fines and court costs totaling $1,647 each. Their newspapers, however, refused to publish the retractions demanded by the Soviet court.

The judge ended the legal action against the two last week, and his decision to report what he termed their "disrespect" to the Foreign Ministry was widely regarded as a face-saving gesture.

The Foreign Ministry had not been expected to expel the correspondents since the Carter Aministration had made it clear it would retaliate against Soviet journalists in the United States.

Whitney and Piper were sued by the Soviet State Television and Radio Committee, a government agency, two months ago because in their dispatches they quoted dissident sources as saying that the televised confession of a Georgian dissident, Zviad Gamsakhurdia, was faked. Gamaskhurdia, 39, was brought to the trial last month and asserted publicly that his confession was genuine.

The Soviets are pointing out that the payment of fines and court costs by the two journalists represents an "indirect" acknowledgement of guilt, and that the entire press in the United States, including the Times and the Sun, had reported that the dissident stated his confession was genuine.

The U.S. businessman, Crawford, who is accused of violating currency laws here, was subjected to long hours of questioning at Lefortovo prison yesterday for the second straight day.

Crawford, 37, was arrested here in June in what was seen by diplomats here as a clear Soviet retaliatory move for the arrest in the United States on espionage charges of two Russian employes of the United Nations.

The Carter administration has refused to view Crawford's case in the same light as that of the two accused Soviet agents.

The indications that Crawford may be put on trial apparently reflect Soviet frustration over the inability to obtain the release of the two Russians in the United States.