Justice Department attorneys want to question Senate investigators who interviewed a convicted embezzler about his relationship with former budget director Bert Lance.

The request to the Senate Government Affairs Committee - which was tentatively approved yesterday - is believed to be the first public acknowledgement that Justice is interested in the testimony of Billy Lee Campbell, who is currently in prison.

Campbell pleaded guilty in September 1976 to stealing hundreds of thousands of dollars from the Calhoun (Ga.) First National Bank while he worked there under Lanre in the early 1970s. He is reported to have implicated Lance in his activities.

But Justice officials cautioned yesterday against reading any great significance into the request, which came in a June 1 letter.

"We're just trying to be though, to complete our record," one knowledgeable Justice official said. "We don't want anyone to say we left anything undone."

Lance, a close friend of President Carter, resigned last fall after a string of revelations about his finances. The Justice Department since has been reviewing Lance's banking activities for evidence on whether to seek in indictment should be reached by the end of the summer.

Investigators are forcusing now on whether Lance's complicated transactions to cover personal loans amounted to a pattern of criminal fraud, according to sources.

The Justice letter to the committee asked permission to review notes of three Senate investigators' meetings with Campbell last Aug. 30 and Sept. 1. It also asked authority to question the three investigators "as part of its investigation of certain activities" at the National Bank of Georgia and the Calhoun Bank.

Justice attorneys expressed surprise that the committee had made the letter public. Senate rules require that both the committee and the full Senate approve any such requests, however.