The D.C. Public Employee Relations Board has rejected a request by a union representing District employes, to reopen bargaining with the city government over a three-year contract negotiated last fall.

The American Federation of Government Employees filed a complaint on May 22 which alleged that the city engaged in unfair labor practices by understating the city's 1985 revenues and by giving misleading warnings of possible layoffs during negotiations.

Addis C. Taylor, executive director of PERB, said yesterday that the board has decided in favor of the District government but that the opinion outlining the board's reason for its decision has not been written.

Mayor Marion Barry issued a statement saying he is "pleased" with the PERB ruling. "The AFGE and all other unions involved in collective bargaining with the District had extensive access to information about the District budget early in the negotiations process so that they could have the greatest possible understanding of the District's financial position," the statement said.

The District government estimated in a mid-year financial report issued in May that its fiscal 1985 revenues would be $41.3 million higher than originally anticipated. Later that month the union accused the city government of understating its revenues by that amount in its contract talks and asked that the talks be reopened.

The three-year contract affects about 10,000 District employes.