Millions of Japanese television sets have not been assessed special duties by the Treasury even though the government found in 1971 tha Japanese producers were illegally selling the sets below cost in the United States, ranking members of the House Ways and Means Subcommitte on Trade have complained.

In a letter to Treasury Secretary W. Michael Blumenthal, the congressmen charged that failure to enforce the anti-dumping laws has cost American workers job and forced American manufacturers to cut back production or transfer their operations overseas.

About $3 billion worth of television sets since 1973 have not been assessed the required duties, although importers have been forced to post a bond to cover potential dumping liabilities.

Chairman Charles Vanik (D-Ohio), Rep. Dan Rostenkowski (D-III.) and Rep. William A. Steiger (R-Wis.) demanded that Blumenthal "report on the reason why the assessment of dumping duties has not taken place and what steps the Treasury Department intends to take to correct this deplorable situation."

The Treasury is also investigating whether there has been a scheme to falsify invoices so importers could avoid paying dumping duties. The department is apparently going to wait until the end of that fraud investigation before levying dumping duties.

President Carter told steel makers last week that the government has been lax in enforcing trade laws such as the anti-dumping statutes and promised that during his administration enforcement would become much more "vigorous."

The three congressmen cited the recent dicision by Zenith Radio Corp. to lay off about 25 per cent of its domestic work force over the next year, and transfer many operations overseas. Zenith now employs about 21,000 workers in the United States and 3,000 abroad.

The Chicago-based manufacturer cited unfair foreign competition when it made the announcement last month. Zenith has appealed to the Supreme Court in a suit to force the Treasury to levy another kind of tariff against several Japanese electronics manufacturers and has filed civil antitrust suits as well against several Japanese firms.

Vanik, Rostenkowski and Steiger said that the Zenith situation is probably another instance where the Treasury's failure to enforce the law "has resulted in a loss of domestic production facilities and jobs which should have never been lost."