The idea was to turn a sandlot near Prospect Park in Brooklyn into a site fit for minor league baseball, to bring professional ball back to the borough 43 years after the Dodgers left.

The multimillion-dollar playing field at the Parade Grounds, opposite the southern edge of the park, would be constructed as a stand-in until a permanent stadium was built in Coney Island. Then it would be left to the city's young players, offering a grand forum for the development of their own baseball dreams.

But this city proposal has run into opposition from many of those it is said to benefit, with users angry over the potential loss of what has turned into a popular spot for soccer and other sports. Residents of Flatbush and other surrounding areas have been circulating petitions calling for more community input into the plan, and local officials have been offering proposals of their own.

Their general complaint is not a new one for City Hall: the stadium's opponents say the Giuliani administration has acted unilaterally in deciding what team to woo to the borough and has kept mum on the details.

"The administration has not been forthcoming with any information despite our repeated written requests for it," said Alvin Berk, chairman of Community Board 14, in Flatbush. "Right now we have no idea how big the field will be, what it will look like, how traffic will be handled and what it means to all the other users of the park.

"We've heard a lot of concerns from residents," he said, "but haven't been given enough information from the administration to even take a vote on the proposal ourselves."

Repeated calls over three days to officials with the city's Economic Development Corporation and the Parks Department produced no details.

Bruce Brodoff, a spokesman for the agency, finally said, "There is nothing to say because everything is still in negotiations. "There are a lot of things that go into this and things can change," he added. "It wouldn't pay to put out a press release."

Edward Skyler, a Parks Department spokesman, floated the idea six months ago, saying that the city would spend $3 million to build the playing field and a 3,000-seat temporary grandstand. At the time, he said that after a 38-game season next summer, the Mets farm team would move to a proposed $20 million stadium in Coney Island that would seat 6,500 people. That would leave the field for tournament-level high school and sandlot games.

Mr. Skyler's comments came after the city had already announced a $2 million plan to upgrade the Parade Grounds, saying the money would be used to build a football field, to refurbish some soccer grounds and to rebuild two baseball diamonds. The notoriously bad drainage and watering systems at the 40-acre site were also to be redesigned.

But if the Mets plan goes through as initially described, it appears that at least two fields will be lost to general use and a third will be taken over for parking, at least temporarily.

Angered by what he sees as the administration's recalcitrance in disclosing its plan, the Brooklyn borough president, Howard Golden, has scheduled a public meeting of the borough's board for today. Mr. Golden's office said the special session at 6 p.m. in Borough Hall was called to force the administration to meet with the community, adding that officials with the Economic Development Corporation and the Parks Department had been invited to speak.

The city officials are likely to be met by a barrage of questions, from why the administration chose a short-season Mets farm team for the site to how other uses for the fields will be curtailed, particularly the youth soccer games now held at the Parade Grounds.

For the last several months, Mr. Golden has accused the Giuliani administration of not acting in the best interests of Brooklyn on the deal. He has said that the administration's refusal to consider other minor league ball clubs is short-sighted, and that a higher-level team -- playing a full season instead of the shorter Single A summer schedule -- will bring more money to the borough and more fans to the games.

In the meantime, parents whose children now play soccer, lacrosse or other field games on the Parade Grounds fear that they will be squeezed out. And those living around the Parade Grounds worry that problems with securing a stadium site in Coney Island will leave the farm team playing in their neighborhood permanently -- bringing with it traffic, unruly fans and parking problems.

Mostly, those opposing the plan say they just want some input before the city's Franchise and Concession Review Committee votes on the plan in two weeks.

"This is a big thing for everyone involved in the Parade Grounds and we really deserved to hear the facts about what's being proposed," said Howard Helene, whose 9-year-old son has grown up playing on the fields. "Maybe this is a good thing for the park but because of the way it's been handled, nobody really knows."