The Carter administration has left unchanged the minimum prices allowed for steel imported into the United States despite threats by the nation's largest steel maker that it would file antidumping complaints against some foreign steel producers if it didn't receive more relief.

The Commerce Department said that the second-quarter prices, known as trigger prices, won't be changed because it is reviewing a number of complaints and suggestions from the steel industry and others and additional issues surrounding the nearly-two-year-old protectionist program.

The trigger during the first quarter averaged $358 per ton of imported steel.

Commerce is reviewing the issue because authority over the program was transferred to it from the Treasury Department on Jan. 2 as part of President Carter's trade reorganization program.

"While this review is not expected to result in major changes in the trigger price levels and will not alter the (price's) conceptual base, it is preferable not to adjust trigger prices until the review is completed," stated a Commerce Department release.

The program setting minimum prices for steel imports was adopted last year to prevent foreign producers from selling steel in the United States at less than it cost the world's most efficient producers -- the Japanese -- to make and ship it.

The trigger prices last were raised in November to affect the first quarter of this year, which began in January. At that time the prices were increased by about 5 percent.

Late last year, however, U.S. Steel Corp. Chairman David M. Roderick said that the trigger price program wasn't keeping underpriced foreign steel out of U.S. markets and that American producers and workers were being hurt.

Roderick said that the company was preparing antidumping complaints against all European steel producers and Japan but that if the trigger prices were raised substantially, the firm might not file any complaints.

A U.S. Steel spokesman said last night that the company wasn't aware of Commerce's action and that it had no comment.

If a major complaint is filed, however, the trigger price program would be suspended, which would mean prices of imports could drop and those goods would flood U.S. markets.

At a press conference yesterday John Greenwald, deputy assistant secretary for import administration, said that he was aware of complaints about the program made by the steel industry but Commerce's action and the consequences of any complaints weren't meant as warnings to anyone.

Greenwald added that if a complaint wre filed and subsequently resolved -- for example if it were withdrawn -- the trigger price mechanism might be reinstated.

The second-quarter trigger price was supposed to be issued about a month ago, but it was delayed because of the transfer of authority, Commerce officials said.