Assistant Attorney General William Bradford Reynolds unveiled a three-inch stack of Labor Department cases yesterday that he said show the government forcing federal contractors to meet rigid minority-hiring quotas.

Reynolds acknowledged that most of the 20 examples were supplied by the construction industry and that a number came from Associated General Contractors, a leading supporter of Reynolds' drive to revise a 20-year-old executive order on affirmative action. But he said the examples, more than half of which took place in 1981 and 1982, did not mean the practice is limited to one industry.

"The president is going to have to make a decision in the very near future," Reynolds said of the seven-month-long dispute that has split President Reagan's Cabinet and much of the business community. He said the Justice Department has completed negotiations with Labor Secretary William E. Brock, who has strongly resisted Reynolds' plan to strip numerical goals and timetables from the affirmative action program for contractors.

The two departments have failed to reach a compromise, despite White House efforts to resolve the issue before it goes to Reagan. Reynolds said "there certainly have been some improvements" in the program under Brock but that changes are needed to prevent future abuses.

Labor Department spokesman David Demarest disputed Reynolds' analysis but said the department is reviewing cases in which "the language may be ambiguous." He said this amounts to "a pretty small number" of the 5,000 cases his department has handled since 1981.

"The statements that seem to trouble them, on requiring contractors to make good-faith efforts to meet goals, those statements don't trouble us," Demarest said. "That is not what we perceive as a quota. We have been opposed to quotas, as have they."

Reynolds said he was releasing the material in response to news media and congressional requests following Attorney General Edwin Meese III's declaration that there is "a litany of cases" involving illegal quotas.

Reynolds said the cases are not "atypical" and that the Labor Department program is based on the idea "that there is a right number for every race and gender . . . that racial balance has to be achieved in order to do business with the government." He said the fact that the program has barred only two companies from government work since 1981 does not reduce its coercive effect.

The companies' names were blacked out, except for a Lenexa, Kan., contractor who has complained publicly about the program.

In one recent case, a Nebraska construction firm was told that "the 21 prior minority employes and the 27 minority applicants in the file for recall will be contacted before any other applicant will be sought." As in most of the cases, Labor officials said the firm had failed to demonstrate "good-faith efforts" to meet hiring goals, but did not mandate any hiring.

Similarly, Labor officials told a contractor in 1982 that it could show good faith by "calling the union local and requesting a qualified minority or female." Reynolds said such remedies -- requiring that minority applicants be screened first -- amounts to racial preference.

One 1981 case, involving a Georgia firm, specified that minorities must be hired at a 50 percent rate until the overall goal was met. Labor officials also said that since the firm had no full-time female construction workers, it had to "make up the female work hours" for the previous year as well as meet future goals. Demarest said the program dropped the use of such "makeup" goals in 1981.

The National Association of Manufacturers has defended the program's value, but it has been criticized by the Chamber of Commerce and construction industry.