George Koch received a temporary setback yesterday in his attempt to introduce new evidence into his suit against the Congressional Country Club.

Koch, who has been on a long crusade against the club for allegedly failing to pay its employes the wages due them, has sought to introduce the results of an investigation into the club by the Maryland attorney general's office.

But a Montgomery County circuit court judge yesterday postponed depositions that Attorney General Stephen Sachs and assistant attorney general David Blum had been scheduled to give on the investigation.

Blum had concluded in a report last summer that Koch's charges of wage violations were essentially correct, and that the club had systematically skimmed thousands of dollars from the pay checks of its employes without their consent. The report found that while Congressional had violated Maryland's wage payment and collection law, no charges could be brought by the state simply because the three-year statute of limitations had run out.

Koch had wanted Sachs and Blum to testify about their findings of illegal activity in order to buttress his own suit to obtain club records that he hopes will prove his allegations against the Potomac club.

Koch's suit, part of his ongoing legal battle since 1977, has become bogged down in what the judge in the case, John J. Mitchell, once termed "a paper war." Koch wants the club records made open to public inspection, and he is contending that as a club member and stockholder he has a right to look at the books.

The attorney for the club, James Thompson, has called Koch's suit a "vendetta" that will violate the privacy rights of the individual members and stockholders. Thompson also said that since Koch's only motive is to embarrass his own club, he has forfeited his stockholder's right to inspect the club books.

The attorney general's investigation, begun in December 1979 after Koch made his allegations public, essentially vindicates at least part of Koch's charges of wage violations.

The report, a memorandum to Sachs dated June 25, 1981, found that "the club for its part seems to have simply perpetrated a system which has been in effect since 1948 and which, according to most accounts, is and was fairly typical of the system used by many service industries in the Washington area and throughout the country."

The report found that the club was essentially deducting 20 percent across the board from the salaries of all of its employes -- the bartenders, waiters, waitresses and cooks. The Maryland wage payment and collection law states that "no employer may take deductions from the wages of an employe" unless the deductions are authorized in writing by the employe, ordered by a court or allowed by a government agency.

The report also found that the club withheld various "special" deductions from the employes in excess of the 20 percent, a practice which stopped in 1977 after Koch began his own private investigation.

The report found that there was no evidence that any of the money skimmed from wages had been funneled back to the management for any other use. Therefore the attorney general's office decided there was no reason to press criminal charges against the club or any of its directors. The report concluded that the money apparently was skimmed from paychecks and distributed to other food service personnel.

However, since the club discontinued the special deductions in mid-1977, and informed the employes, the three-year statute of limitations had run out for prosecuting civil claims, Blum said.

"It should be noted," the memorandum said, "that the club appears to have stopped the 20 percent deduction and the 'special' deduction because of the commendable efforts of Koch."

Mitchell said he will specify later when the depositions can be taken. Meanwhile he is still considering a request by the club's lawyers to hold Koch in contempt of court for talking to reporters about the suit.