Prince George's County officials were happy when they received $1.6 million from this year's General Assembly session to start the wheels turning on a long-planned new government complex in Hyattsville.

What they did not take into account was the opposition they would encounter from residents and store owners of the two-block-square area facing the site for the $27 million Justice Center. Many of the neighbors complain that they have not been consulted about the plans.

"This was a very sneaky thing that was done," said Millie Wilson, the office manager of the Hyattsville Animal Hospital, which has been in the 5000 block of Rhode Island Avenue for 23 years and would be replaced by a new police station and courthouse. "There's been a conspiracy of silence."

According to the plans that County Executive Parris Glendening used during his campaign to win state funding, he wants to renovate a county services building on the seven-acre parcel bounded by Rhode Island Avenue (Rte. 1), 43rd Avenue and Farragut Street and add the new courthouse; the new police station, and a 700- to 900-car parking garage. The project, scheduled to be completed in September 1988, is to be paid for with state bond money and voter-approved county bond money, and the garage will be financed by a separate, semiautonomous parking authority. That authority was created after voters in November turned down a referendum seeking county bonds for the garage.

The proposal has been in the planning stages for more than a year, and Glendening pushed hard to woo County Council members and the county's state legislative delegation this winter. But residents say they were not consulted about the project and heard about it from news reports and neighborhood gossip.

"There was no communication from the county executive's office," said Harold Eccleston, the owner of the 33-unit Chelsea Square apartments that occupy the site designated to become the parking garage. "In my opinion, that was deliberately done so that there was no chance to mount informed opposition to it."

Eccleston, 40, and his brother Ken bought the brick garden-style apartments in 1981.

Since then the Ecclestons have repaired and renovated the four, 40-year-old buildings, have planted flower beds and have fully rented the two- and three-bedroom apartments.

"Now it looks like we're going to be selling it to the county," said Harold Eccleston of Silver Spring.

He wrote letters to all members of the General Assembly urging them to delay the funding for the project because it would add to the area's traffic congestion and disrupt a recently restabilized neighborhood.

Laurie Fitzgerald, 30, who lives with her husband John, 31, and their 11-month-old daughter Tammy and is Chelsea Square's resident manager, said that the economical rents, which range from $395 to $465 a month, are a major reason why they live there. John Fitzgerald is a graduate student at the University of Maryland.

"We're trying to live on $7,000 a year right now," she said. "There's no place else you can live for that."

County officials said they did not involve local residents in the planning for the center because they considered the first hurdle for the project to be gaining General Assembly approval for the funds that will be used for land acquisition.

"Before we got the bill through the General Assembly, it didn't make a lot of sense to go into the community and stir this up," said John Davey, the county's deputy chief administrator in charge of the project.

Councilman Anthony Cicoria, who represents the district, voted to support the project. But he said this week that he was not aware that area residents would oppose the proposal. "I think it's needed . . . . but I think the people in the area should be aware of what is happening."

Davey said that the county will attempt to purchase the land needed for the project or seize it by eminent domain if necessary. But, he added, "We do not want to start off in a hostile situation. We are not going to go in there with a bulldozer."