The Senate permanent subcommittee on investigations, which has been digging into labor racketeering and other corruption since the 1950s, is itself under investigation over allegations that one or more staff members may have misused congressional funds.

Subcommittee staff director Daniel F. Rinzel said yesterday that the General Accounting Office is examining "discrepancies" that the panel turned up in its travel funds and other expense accounts.

Rinzel said that Sen. William V. Roth Jr. (R-Del.), chairman of the subcommittee and its parent Governmental Affairs Committee, "called in GAO to do a review of all our books here. He wants to know what happened, how it happened and make sure it doesn't happen again."

With a $1 million budget and more than 25 staff members, the subcommittee is among the most visible on Capitol Hill, frequently making headlines on subjects such as money laundering, union corruption, and health-care fraud. Asked about the probe, Rinzel said: "Let's face it, it's embarrassing."

Katherine C. Bidden, the subcommittee's chief clerk since 1981, resigned in March after subcommittee officials asked her about travel and other expenses she charged to the panel, Rinzel said. Bidden, who was paid $32,000 a year, could not be reached for comment.

Rinzel said there is no question that "some money was improperly spent," which he estimated at "several thousand dollars" or more. He said it will not be known whether the total is larger or whether other staff members made improper billings until the GAO completes its review of subcommittee accounts for the last five years.

Roth will refer the findings to the Justice Department if necessary and plans to tighten spending controls in the parent committee, Rinzel said.

The subcommittee, which helped send former Teamsters president Jimmy Hoffa to jail, compiled a storied history under the 18-year chairmanship of Sen. John L. McClellan (D-Ark.), who stepped down in 1973. Robert F. Kennedy was its counsel and his brother, Sen. John F. Kennedy (D-Mass.), a committee member when McClellan began his racketeering investigations.

The panel's targets have ranged far and wide since Roth took over in 1981. Two years ago, for example, Roth accused the GAO of wasting almost $13 million on a virtually worthless computer system.