A presumed gubernatorial candidate, Thomas Suozzi, yesterday said he favors providing state incentives for the development of abandoned industrial sites.

The Nassau County executive was the keynote speaker at a conference on reusing contaminated lands, or brownfields, for low- and middle-income development. About 300 government officials, city planners, developers, and community organizers attended.

“The key with brownfields is for the government to help create an environment that will help unleash the power of the private marketplace,” Mr. Suozzi, a Democrat, said. “It will not happen on its own. We need to provide incentives.”

Mr. Suozzi still has not officially announced his candidacy, but he shows all the other signs of being serious about an election bid and has raised about $5 million. While Attorney General Eliot Spitzer is evidently the man to beat for the Democrat gubernatorial candidacy, the Long Island politician appears to be gaining steam.

Yesterday, Mr. Suozzi said that while he and Mr. Spitzer both may pledge to support the conversion of brownfields, his background as a certified private accountant and his track record as a county executive gives him an advantage. “In this instance, I can say I can do it because I’ve done it,” he told The New York Sun.

Indeed, Mr. Suozzi has received national recognition for his work in Glen Cove, a neighborhood on Long Island with a successful brownfield redevelopment project.

There are scores of potential redevelopment sites in New York City, primarily former manufacturing areas that are filled with hazardous materials, although the state monitoring body said it does not track the actual number.

A swift development boom was expected two years ago after the New York State Legislature completed a seven-year effort to pass environmental legislation to clean up the sites, providing tax breaks and liability insurance. Developers have not seized on the new opportunities as rapidly as predicted, however.

“The big challenge is you got started and the costs turned out to be more than you thought, and it’s a black hole from which you never emerge,” an associate professor of real estate at Baruch College, Barry Hersh, said. “You need clarity.”

Yesterday’s conference, hosted by the nonprofit organization New Partners for Community Revitalization, aimed to unite the parties involved and encourage development particularly for low- and middle-income neighborhoods.

The state Department of Environmental Conservation, which oversees the brownfield redevelopment program, answered community groups and developers who said the program has been too cumbersome. The official directing the program, Dale Desnoyers, said the department is aware of the issues and that new rules are under consideration. In the meantime, he encouraged developers and community organizations to take advantage of the “tremendous benefits” being offered by the state.

It’s a message an organizer of yesterday’s event, Mathy Stanislaus, said the city would be wise to heed. Most of the brownfields in the city border disadvantaged neighborhoods, Mr. Stanislaus, a director of New Partners for Community Revitalization, said, and with the hot real estate market encroaching on previously untouchable neighborhoods such as Hunts Point, the poor could be squeezed out of the city.

“The real importance of clarity is with low- and middle-income development,” Mr. Stanislaus said, because that is where there is the least incentive to develop. While the financial benefits may not be immediately evident, if done right, he said, “brownfields could be a great source of money.”