The fraud unit of the U.S. attorneys' office here and FBI agents are looking into the alleged misuse of overtime claims by employes of the U.S. Commission on Civil Rights, according to federal investigators in the District of Columbia.

The investigation, centering on seven employes, began last March after the commission conducted an inhouse probe and alerted the FBI.

Joan Kelly, a spokeswoman for the commission, said yesterday that the employes under suspicion range in rank from GS-6 to GS-9 and include four secretaries and an equal opportunities specialist.

According to Kelly, the commission discovered an irregularity involving an overtime claim last February and asked for an investigation by the Justice Department.

The Commission has since found alleged abuses involving faked overtime slips and failures to record annual leave properly, Kelly said.

These alleged abuses involved $11,000 over an 18-month period reviewed from September 1976 to February 1978, she said. The amount per person ranges from $300 to $5,000, she said.

Two of the seven employes involved have left the commission, one has been fired, one is on extended leave and the other three have been notified that an adverse action is to be taken against them, Kelly said.

The commission is an independent government agency established by Congress 21 years ago to investigate compliance with civil rights laws and prepare studies in that area.

Rep. Gladys Noon Spellman (D-Md.) who chairs the House subcommittee that oversees time and attendance of government employes, said yesterday that she has asked the General Accounting Office to investigate the extent of overtime abuses.

"We want to know how easy it is to falisify records," she said. "If we find it's widespread, we will take legislative steps to prevent it."

The Justice Department also is investigating allegations that some employes in the U.S. Forest Service's Rosslyn office may have submitted false overtime payments that cost taxpayers between $50,000 and $100,000, Forest Service Officials have said.