The D.C. Lottery Board has signed a contract with an Atlanta firm for operation of the city's instant lottery game without resolving complaints from two losing bidders who accused the board of violating its own guidelines when it selected the winner.

In a letter sent yesterday to the U.S. General Accounting Office, Brant Coopersmith, chairman of the D.C. Lottery and Charitable Games Control Board, said the board signed the contract Monday in order to prevent the city from losing an estimated $500,000 a week in lottery revenues, 30 percent of which would go to the city.

"The instant game will generate a reserve critical to the operation of the District of Columbia lottery," continued Coopersmith in his one-page letter addressed to GAO Associate General Counsel Mike Boyle, "therefore the award cannot be delayed."

The contract signed Monday provides for starting the lottery in mid-August. It is expected to generate about $10 million in ticket sales over the first 8-10 weeks.

If the contract were signed later, Coopersmith said, the start-up date would have to be pushed back and the city government would get fewer funds by Sept. 30, the end of the current fiscal year.

The final contract with the joint venture team of Scientific Games Development Corp. of Atlanta and Games Production Inc. of Washington comes less than a month after two unsuccessful bidders complained to the board of its actions and asked that the award of the contract be set aside.

GAO officials could not be reached for comment late yesterday.

Raymond A. Mott, president of Raven Systems and Research Inc. of Washington, one of the losing firms, said, "We've been had and ripped off. What they have done is made a mockery out of due process."

"Raven has worked with them, in terms of filing the protest in good faith, and the city has awarded the contract in bad faith," he said. "As far as I'm concerned, it's a real slap in the face."

Coopersmith said the board has not been unfair.

"If the companies are damaged they can get damages," he said. "But if the city loses revenue, it can never recover. If he Mott should be vindicated, then he can be recompensed. We don't want to injure any business."

Officials from Glendinning Companies Inc. of Westport, Conn., the other losing firm, could not be reached from comment yesterday.