HOBOKEN— For more than a decade, NJ Transit has had its eye on adding a new light rail station in Hoboken's northern end. But a deal for the project —made with a Christie-connected developer—was kept a secret for nearly nine months, and the agency still isn't willing to release further details.

NJ Transit and the Rockefeller Group inked a non-binding agreement in June to continue with plans for a station near Clinton and Grand streets in the northern section of the city. Mayor Dawn Zimmer wasn't apprised of the agreement, and filed an Open Public Records Act request last month to obtain a copy. She received the agreement, but said that a site plan referenced in the documents was missing (the same site plan was not included in NJ.com's copy of the agreement).

She has yet to receive the site plan, and said that NJ Transit told her that they couldn't immediately find a copy. Zimmer said that the secrecy of the agreement, though preliminary, raised several "red flags."

“The question is why was this done in secret?" Zimmer said. “If this is a great public benefit, why aren’t they involving the city?”

A spokesman for NJ Transit refused to comment on the agreement. Representatives for the Rockefeller Group would not immediately comment.

The prospect of adding a new light rail station to the city isn't new. When the Hudson-Bergen line first came to Hoboken in 2002, planners anticipated an eventual need for a station in the far-north sector of the city, according to the agreement.

“System planners recognized that neighborhood ridership demand in this portion of the city would steadily, increase, necessitating a station to serve residents, businesses and visitors," the agreement states.

The so-called “memorandum of understanding,” which is described as a preliminary agreement to continue planning a possible light rail station, isn’t binding for NJ Transit or Hoboken, and it was up to the Rockefeller Group to obtain municipal approvals for construction.

But the city wasn't included in discussions leading up to or following the June agreement, which is signed by outgoing NJ Transit Executive Director James Weinstein and Clark F. Machemer, vice president of the Rockefeller Group. Zimmer said that the city should have been involved in the process for a number of reasons, including that a better location for the station — one that may benefit businesses and other developers — may exist.

Since 2008, the Rockefeller Group — under the name Park Willow LLC — bought up more than a dozen properties in Hoboken, according to property records. The developer proposed building a 40-story office tower in the area, a project that is at the center of allegations that Gov. Chris Christie's administration withheld Hurricane Sandy relief funds to promote the development.

Last month Zimmer accused Christie of threatening to hold back relief money if she didn't back the Rockefeller Group's project. His administration has denied the allegations. These claims came as the Christie administration became embroiled in the George Washington Bridge closure scandal, as well as allegations that Hurricane Sandy relief funds were improperly channeled to a Belleville senior center and housing complex.

The Rockefeller Group's plans for the area were largely stalled in April, when the city planning board voted against designating three blocks of the Rockefeller Group’s property in need of redevelopment, the Star-Ledger reported. The Port Authority of New York and New Jersey had provided a $75,000 grant to fund the development study that recommended the three blocks.

At the time of the June memorandum of understanding, the Rockefeller Group was represented by Wolff & Samson, the law firm headed by Port Authority chairman David Samson. The developer severed ties with the law firm late last month.

In addition to a new light rail station, the preliminary agreement included improvements to sidewalks and nearby roads. These proposed improvements included a new road connecting Clinton and Adam streets, with a car drop-off area, as well as a “pedestrian-friendly road” and “general road and landscape improvements, according to the agreement.