Failure of the U.S. Court of Appeals to reverse a district court decision could cripple four of Australia's biggest corporations, according to an unprecedented submission by the Australian federal attorney general.

Peter Durack also claimed that the original U.S. court decision could "affect the financing of resources projects and the attraction of foreign investment" in Australia.

The Australian government's blunt comments are contained in a friend of the court memorandum filed with the U.S. court of appeals against a decision last January in an Illinois U.S. District Court.

The district court found in favor of the Westinghouse Corp. in an antitrust suit against 29 American and foreign uranium producers, including four Australian companies.

Westinghouse claimed the 29 corporations organized a price-fixing cartel in the early '70s to boost the price of uranium contrary to American law.

The Australian companies refused to appear in the American proceedings, and executives of all of them have since avoided visiting U.S. territory lest court action be taken against them.

On two occasions -- in late 1976 and again this year -- the conservative Australian government of Prime Minister Malcolm Fraser has legislated to protect the four Australian companies. In 1976, it rushed through a law permitting them to withhold evidence from American courts and in March 1979 passed another law prohibiting enforcement on Australian territory of any judgment made by the American court in this matter.

In its case to the U.S. Court of Appeals, the Australian government points out that Westinghouse has asked for triple damages and that the district court said the judgment against the four Australian companies, yet to be determined, could run into "hundreds of millions of dollars."

Durack's strong words were inspired partly by the size and local importance of the four Australian companies. All of them are in the top 100 of indigenous Australian corporations and one -- Conzinc Rio Tinto of Australia Ltd. -- is the second-largest Australian company with a market share valuation of about $15 billion. The others are Queensland Mines Ltd., Pancontinental Mining Ltd. and Mary Kathleen Uranium Ltd.

"This outreach of American antitrust laws to affect nationals and residents of other countries, including Australia, does have very serious implications," Durack said.

A huge judgment against the four Australian companies "would seriously impair the ability of the Australian companies to attract the large amounts of risk capital required for the development of the nation's resources and their export," the submission said. It added that each of the companies could be crippled if a huge triple-damages judgment is enforced.