The usual Philadelphia "land-grab" squabble includes angry rowhouse neighbors lobbing accusations at powerful institutions.

But in a legal battle over highly prized land, the University City Science Center has accused the city's Redevelopment Authority of a "land grab" of its own.

The science center, based at 37th and Market streets, has filed a lawsuit to block the RDA from seizing control of two undeveloped parcels on the center's West Philadelphia campus.

The suit, filed May 28 in Philadelphia Common Pleas Civil Court, alleges that the RDA illegally declared the center in default for missing deadlines to develop the parcels, both on the southwest corner of 38th and Market streets.

"The Redevelopment Authority, 'seemingly oblivious to the global financial collapse,' is in violation of its agreement with the science center and should be blocked from declaring the science center in default," the center said in a statement yesterday.

The center, founded in 1963, describes itself in the complaint as "an engine of economic growth for Greater Philadelphia."

"This unprovoked 'land grab' by the RDA would break up the campus and put at risk the economic engine," the center said in its statement.

The center signed an urban-redevelopment agreement with the RDA in 1965.

An October 2006 amendment said construction on the two parcels (3800 and 3850 Market St.) should start on or before June 1, 2007, and be completed by May 31, 2009.

About February 2008, the science center began talks with Genzyme Inc., a Cambridge, Mass.-based global-biotechnology company, to open a manufacturing site here.

But by August 2008, Genzyme put its plans for a "major new manufacturing and product development site in North America" indefinitely on hold as a result of the "global financial meltdown," according to the suit.

According to the complaint, a provision in the agreement "bars the RDA from declaring a default for 'unforeseeable causes' beyond the control and without the fault of the science center."

The meltdown "devastated the real estate market, brought commercial lending to a sudden halt and cut off demand for construction of new office, incubator and research facilities," the suit said.

Doug Oliver, a spokesman for Mayor Nutter, said he couldn't comment on active litigation.

But generally, he said: "It is of concern to the RDA if a property is not being developed. We then would want to seek new redevelopment opportunities."

In January 2008, the science center, working with the city's Commerce Department, launched a $4 million Market Street Revitalization Project, to transform Market, from 34th to 41st streets, with trees, sidewalks, benches, bike lanes and improved pedestrian lighting and crosswalks, the suit said.