Members of the D.C. police department, in a mail ballot, have ratified a three-year contract with the city government, International Brotherhood of Police officials announced yesterday.

The agreement, the first labor contract negotiated under the District of Columbia's complex new personnel law, was approved by a vote of 616 to 420, despite vehment opposition from rival unions that branded it a sellout.

The contract provides for bonus payments, in place of increases in the wage base, of $1,400 during the first 18 months. A general wage increase of $1,000 is provided in the second half of the second year, and a cost-of-living increase of 7 percent to 9 percent will be provided in the third year. In addition, the contract provides increased health care benefits and calls for a revision of police disciplinary procedures, including the elimination of trial boards.

Under the constitution of the IBPO, a ratification vote was not required, but local president Larry Simons put the contract to a vote to support his claim that the rank and file approved it. Fewer than half the eligible police officers returned the ballots, which Simons said is a reflection of the fact that "people who are satisfied don't express it."

He said he was "a little less than pleased" that there were more than 400 negative votes. He and the other leaders of the union, he said, "learned something from this. Next time we'll go for more in the wage base."