The University City Science Center is trying to stop the city's Redevelopment Authority (RDA) from seizing two parcels in its science park campus in West Philadelphia because the center missed deadlines to develop the land.

In a lawsuit filed Friday in Common Pleas Court, the Science Center said the RDA had no legal grounds for taking back the lots, which comprise most of the south side of the 3800 block of Market Street and currently are used for parking.

The largest urban research park in the nation, the center was founded in 1963 with support from the city and RDA to oversee the development of Market Street between 34th and 39th Streets.

On Sept. 8, 2008, the RDA found the Science Center in default of a decades-old plan to redevelop the parcels. Under an agreement that had been amended nine times, most recently in 2006, development was to have been started by June 2007 and finished by May 31, 2009.

In its lawsuit, Science Center attorneys said that challenging economic conditions in real estate and financial markets had delayed the project, and that the RDA was "seemingly oblivious to the global financial collapse."

A provision in the RDA's redevelopment agreement with the center bars the authority from declaring default for "unforeseeable cause."

However, the RDA already has taken legal steps to seize title to the land.

The Science Center, next door to the University of Pennsylvania and Drexel University, has served as a business incubator for companies developing commercial applications in medicine, science, and technology.

The RDA's action against the center is part of a broader effort to aggressively enforce redevelopment agreements and prevent developers from holding land indefinitely.

Doug Oliver, a spokesman for Mayor Nutter, declined to comment because the matter was now in litigation.

Michael Sklaroff, an attorney for the Science Center, said in a statement that the center had been trying for two years to work with the RDA to revise its development timetable to reflect current economic conditions.

"Unfortunately," he said, "we will now have to resolve through the courts what we had sincerely hoped to accomplish by mutual agreement."