Secretary of Commerce Juanita Kreps is expected to visit Saudi Arabia later this month as part of a continuing effort by the Carter Administration to demonstrate friendship toward that country in the wake of the Iranian crisis.

Earlier this week, the administration sent a squadron of F-15 fighter planes to Saudi Arabia in an effort to show continued U.S. support for the Saudis.

The plans for Kreps' visit -- tentatively set for Jan. 25 -- come as oil production in Iran has virtually stopped. Officials said she is expected to discuss the Iranian oil situation and the impact on the U.S. of the recent OPEC price increases.

One Commerce Department official said Kreps visit would "reaffirm our interest in Saudi Arabia."

A State Department official, noting that Saudi Arabia is the seventh largest export market for the U.S., said: "The primary purpose of the visit is to strengthen economic ties."

But another recent development may inhibit investment by American companies in Saudi Arabia.

A U.S. District Court Judge in San Francisco last Friday ruled that mere compliance with laws barring companies from taking part in anti-Jewish boycotts does not free those same firms from being sued under the antitrust laws.

Judge William A. Ingram refused a petition by Bechtel Corp. that a consent decree it signed to settle an antitrust suit be set aside.

Justice accused Bechtel of anti-competitive behavior for allegedly refusing to deal with U.S. persons and companies blacklisted by the Arabs.

Bechtel and Justice settled in January, 1977. Since then, legislation has been enacted that forbids many of the same boycotting activities that Justice alleged against Bechtel.

Bechtel argued that, in light of the anti-boycott measures enacted in the Export Administration Amendments of 1977, applying antitrust laws is "overly stringent," unnecessary," and "obfuscates the intent of Congress."

Moreover, Bechtel claimed that Justice was extending the reach of the antitrust laws "extraterritorially."

Leading business and Jewish groups submitted briefs in the case. The Anti-Defamation League of B'nai B'rith, for example, supported the arguments by the Justice Department that antiboycott laws do not supercede antitrust laws.