The Prince George's County Council voted 6 to 3 yesterday to create an Office of Labor Relations to conduct negotiations with county employe labor unions, hear grievances and oversee implementation of contracts.

County Executive Parris Glendening proposed the office as a way to cut the costs of negotiations, which have been conducted by a Washington law firm the past four years, and to improve labor relations.

Labor unions supported the proposal but several council members argued against it, saying the county's fiscal problems and the possibility of layoffs should preclude establishing a new department.

"Government seems incapable of controlling super growth," said council member Sue V. Mills, adding that outside contractors are usually cheaper and, if not, can be easily replaced.

An aide for Glendening said the new office would cost $160,000 the first year, including one new employe. The remainder of the staff would be transferred from existing agencies.

Mills voted against the measure, joined by council members Anthony Cicoria and Floyd Wilson, who had supported the proposal in a previous council committee vote.

In other action, the council approved, 6 to 0, an appropriation of $2.4 million in surplus funds for the purchase of about 200 new police cars and to cover higher-than-expected health insurance claims. Some members had balked at the proposal, saying the money should be distributed more evenly among other agencies. But yesterday the measure passed without discussion after police chief John McHale said the cars were needed to replace overworked cruisers and unmarked detective cars.