The chairman of the Equal Employment Opportunity Commission said in an interview yesterday that a 1971 Supreme Court case allowing the use of racial percentages in judging discrimination has been "overextended and over-applied."

EEOC Chairman Clarence Thomas said the decision has been wrongly stretched to require that blacks and women be hired in proportion to their numbers in the work force.

The EEOC has been reviewing federal discrimination guidelines for the last three months.

There are legitimate "race-neutral" job requirements, such as educational tests and strength tests, that might fairly and unintentionally act to limit the percentage of women or any one racial or ethnic group at a job site, Thomas said.

He also endorsed the Reagan administration's position that findings of discrimination and remedies for discrimination should be limited to individuals who have been victims and not extended to "all blacks or all women because an individual has suffered discrimination."

"I'm not saying Griggs v. Duke Power Company is bad law," Thomas said. "In that case they were asking that workers have a high school diploma to dig ditches. But the way Griggs has been applied has been overextended and over-applied. You get people now saying if you don't have a certain number of women or blacks on the job then you are guilty of discriminating . . . if it's an engineering job and you don't have a certain number of blacks because few blacks have engineering degrees there are people who want to ask if you . . . need an engineering degree . . . . That's going too far."

The decision has been interpreted to mean that a company abiding by anti-discrimination laws should have approximately the percentage of minority workers as there are minorities in the "relevant workforce" -- minus 20 percent.

Thomas, whose agency voted in September to review affirmative-action guidelines as well as federal government guidelines for hiring, said recent Supreme Court decisions, such as the Memphis firefighter case in which the court ruled that whites with senority should not be laid-off before more recently hired blacks to preserve racial balance, are evidence that the court has "modified Griggs."

Barry L. Goldstein, a lawyer at the NAACP Legal Defense and Education Fund Inc., said the Griggs case was the "foundation of antidiscrimination law" in hiring.

"Why the bureaucracy would call into question a principle established by the Supreme Court when they have no particular case to do so I don't understand," said Goldstein.