The federal government has reaffirmed it plans to sell Plum Island, finalizing the environmental review of the animal disease research site off Long Island, even though environmental regulators and some lawmakers say there's not enough information about the effects of selling it.

The General Services Administration and Department of Homeland Security issued what's called a "record of decision" Thursday night. The document marks one of the last steps before a sale.

Congress voted in 2009 to close the laboratory, which opened in 1954. Sale proceeds would go toward moving the research to Kansas State University.

A GSA environmental study in June suggested homes might be built on the island. Environmental groups want it to become a nature preserve. Some members of Congress want to stop the sale of the island 100 miles east of New York City.

The two agencies said in a statement they issued the record of decision after considering "all the factors discovered and analyzed" during the National Environmental Policy Act process.

When the timeframe for the laboratory's relocation is known, the agencies said, they will re-examine the environmental impact statement "specifically for the purpose of ensuring that it reflects the then current knowledge of the conditions on the property."

There's been no estimate of what the 843-acre island could fetch at auction, but some lawmakers insist it will barely put a dent in the estimated $1.1bn cost for the new laboratory in Manhattan, Kansas.

Environmentalists have sounded alarms that selling the island would jeopardize endangered terns, seals and other wildlife, and the federal Environmental Protection Agency raised some red flags earlier this month.

The island provides "important habitat for a number of species," and the GSA hadn't done a detailed enough evaluation of selling the island, regional EPA administrator Judith Enck said.

The GSA has defended the environmental study.

In 2007, the New York state department of environmental conservation said there appeared to be no existing environmental threats on the island, noting that hundreds of tons of contaminated soil had been removed from landfills and other areas there.

Meanwhile, there are other moves to stop the island's development.

US senator Richard Blumenthal, a Connecticut Democrat, and US congressman Timothy Bishop, a Democrat from Long Island, have introduced a proposal to stop the sale altogether. "My concern is the unknown and uncertainty," Blumenthal said recently, adding that he wanted the island preserved as open space.

And the local town board approved new zoning laws Tuesday that would prevent any significant development of the island. Under the zoning rules approved unanimously by the Southold town board, the bulk of the island would be preserved as a conservation district while laboratory research would be allowed on part of it.