Lawyers and investigators in the Education Department's Office of Civil Rights have been notified by their superiors that they will be required to undergo full security-risk checks.

The order, in an April 14 memo from Harry M. Singleton, the assistant secretary for civil rights, announces a new requirement in that office for a "critical sensitive" clearance, the equivalent of top secret.

This includes a full background field investigation and directs the employes to sign a waiver of privacy for all medical records, including psychiatric records.

Lawyers in the civil rights office, who asked not to be identified, said they suspect that the policy change may be an effort to uncover personnel who have leaked information critical of the Reagan administration's civil rights policies.

Several current and former OCR employes said that past procedure has been to require a security clearance for top-level decision makers. But the current order will require clearances for about 650 of the office's 1,000 employes. "This is going to cover everybody but the janitors," one affected lawyer said.

David Tatel, who headed the Office of Civil Rights from 1977 to 1979, before Education was separated from the old Department of Health, Education and Welfare, said, "I had a clearance, but that was because I was the head of the agency. I don't believe anyone else had one. I don't see why they would need clearances--unless maybe they've got them investigating civil rights violations in the Soviet Union."

Rep. Don Edwards (D-Calif.), chairman of the House Judiciary subcommittee on civil and constitutional rights, said, "In my 20 years in Congress, I have never heard of a request for security investigations of persons employed by federal civil rights units."

The order comes against a backdrop of administration interest in a government-wide revival of the Federal Loyalty-Security Program of the 1950s. Last month, in a directive aimed primarily at curbing leaks of classified information, President Reagan also ordered creation of an interdepartmental group to recommend "appropriate revisions" in the personnel security program.

According to an interagency study that led to Reagan's March 11 directive, the executive order that set up the loyalty program, issued by President Eisenhower in 1953, "seriously needs revision to take into account subsequent court decisions and changes in government organization."

It is the same 1953 order that is being used as the basis for the new security checks in the education department. The Eisenhower order states that "the interests of national security require that all persons privileged to be employed in the departments and agencies of the government, shall be reliable, trustworthy, of good conduct and character, and of complete and unswerving loyalty to the United States . . . ."

Revamping that order, the interagency study said, "would be helpful in streamlining the authority of agencies to revoke security clearances and take other personnel actions in the interest of national security . . . . All agencies should be encouraged to place greater emphasis on protective security programs."

Under the Eisenhower program, a full field investigation was initially required for all posts designated by department or agency heads as "sensitive by virtue of the material adverse effect on the national security that an occupant of such a position could cause."

But since 1965, according to a new report by the American Enterprise Institute, a distinction has been drawn between "noncritical-sensitive" and "critical-sensitive" positions. Ordinarily, only those in critical-sensitive positions receive a full field investigation, including interviews with old employers, supervisors, fellow workers, neighbors and school officials.

Meanwhile, largely as a result of federal court decisions, "disloyalty" and "subversion" have been virtually abandoned as grounds for denial of government employment. Since 1977, the Office of Personnel Management, which conducts security clearances for 55 federal agencies, has stopped asking applicants about past or present membership in the Communist Party.

"It essentially has been gutted," Justice Department spokesman Art Brill said. "It's in disarray."

Joseph Morris, OPM general counsel, said yesterday that under the president's new directive, the OPM will be reviewing clearances at other agencies as well. He said that the problems at the Education Department, which was created in 1979, have been more serious because it is a new agency and very few clearances had been conducted.

George Woloshyn, OPM's deputy associate director for compliance and investigation, said that, under the law, those Education Department employes should have had clearances already because of the sensitive information that goes through the Office of Civil Rights, and that the department is now simply bringing the workers into compliance. He said a number of Education Department employes outside the Office for Civil Rights will also be cleared.

Woloshyn said the decision is not an attempt to harass personnel in the Office of Civil Rights. "There's nothing negative, nothing scurrilous or conspiratorial about it," he said.