Forest City Ratner’s $4 billion Atlantic Yards development project will be delayed by an additional six months or more in the wake of a ruling by a state Appellate Court.

The court rejected a motion put forth by the Empire State Development Corp. to dismiss the lawsuit filed by nine property owners in the footprint of the project challenging the use of eminent domain. The ruling has forced the developer, Bruce Ratner, to reverse a pledge that ground for the project would be broken by the end of the year.

“While the Appellate Division Second Department’s decision to hear the case may delay the project for approximately six months let me be clear that the project will go forward,” Mr. Ratner said in a statement. “Atlantic Yards will be built and it will create thousands of needed jobs and affordable homes. This is all the more important as our City and country confront one of the most difficult economic downturns in history. We are as committed as ever to the development of this project and will continue to work with the City, State and local leaders to ensure that it goes forward.”

Plans for 16 skyscrapers, an 18,000-seat basketball arena for the Nets, and thousands of apartments at a site at the corner of Flatbush and Atlantic avenues has been affected by a string of legal challenges brought by residents and the ongoing credit crunch.

Opponents to the project have objected to both its size and the use of eminent domain by the state.

The legal director for the opposition group Develop Don’t Destroy Brooklyn, Candace Carponter, said the ruling is further proof that the project may not go forward at all.

“Though Ratner claims that he’ll ‘break ground’ for his Atlantic Yards proposal in December, he cannot do so unless New York State uses eminent domain to seize the owners’ and tenants’ properties and give them to him as planned. But the plan is now in doubt,” Ms. Carponter said in a statement.

A spokesman for the ESDC, Warner Johnston, said: “We do not comment on pending litigation.”