The Prince George's County Justice Center opened yesterday in Hyattsville seven months late and more than $2 million over the construction budget.

Prince George's County officials said the project, originally scheduled for completion in December 1989, is costing $2.5 million more for construction than the contracted price. The officials declined to say whether there were cost overruns in other areas of the project, and could not explain discrepancies in original cost projections for land acquisition and estimated final figures.

The project, architecturally distinctive with gazebos, archways and a football-field-sized plaza, includes the new Hyattsville District police station, a jail work-release facility, and a $12.3 million, 600-space underground parking garage.

Years in the planning, the $31.15 million Hyattsville Justice Center was designed to replace a dilapidated police station and to spur the rehabilitation of a rundown section of downtown Hyattsville along Rhode Island Avenue. The complex includes land bought with $1.6 million in state funds for a proposed state court building.

The district police station adds much needed space to accommodate the expanding force and also provides officers with a secure facility. The lack of secure prisoner processing areas in the old district station was widely blamed for the 1978 deaths of two officers who were shot by a prisoner.

"We wanted to spend whatever was necessary to get the job done and to provide Hyattsville with this beautiful facility," County Executive Parris N. Glendening said in an interview. "We wanted to give Hyattsville something that it could be proud of, and I think we've done that."

Glendening said he was aware that the project had incurred "several million dollars" in cost overruns, but he said that he did not know the exact amount.

"I was just conceptually involved. I couldn't tell you what the dollar figure is," he said. "We decided we would spend whatever is necessary to get the job done . . . . We decided if there were cost overruns, that's okay."

Major F. Riddick Jr., director of the county Office of Management and Budget, said the county has tentatively approved $900,000 in additional expenses for the $19 million construction contract with the A.S. McGaughan Co., of Bethesda. At least $1.6 million more in construction expenses are in dispute, Riddick said. Riddick declined to discuss further the cost overruns or the delay.

"There are some outstanding claim issues that we will not refer to that we feel might end up in court," Riddick said.

Contractor A.S. "Mac" McGaughan declined to comment on the construction delays or cost.

Robert Platky, director of the county Office of Central Services, also refused to say when the county originally expected the project to be completed or how much over budget it is.

"I know we're not going to give you that one," Platky said, referring questions to Glendening's spokesman. "I don't think we want to get into that. In fact, I know we don't want to get into that."

Sources familiar with the project said there have been serious disputes between the county and the contractor almost from the beginning. Specifically, sources said the county contends that hundreds of thousands of dollars in cost overruns were caused when subcontractors did not complete work on schedule. The sources said also that there were numerous design changes that delayed the project and added to the cost.

Riddick said yesterday that the county had projected the total cost of the project at $31.15 million. However, county documents filed with the Maryland Department of General Services show that the projected cost in 1989 for the Justice Center, parking garage, land acquisition and related utility and excavation work was $25.9 million. Riddick said he could not explain the difference.

County officials said the $31.15 million included $2 million for property acquisition. However, county records sent to the state show that at least $3.2 million was spent to acquire and clear land for the Justice Center.

Riddick said he could not explain the $1.2 million discrepancy but that it would be investigated.