Five months before renovations are set to begin at Nassau Coliseum, the project's Brooklyn-based developer has filed suit against the firm it brought in to create an adjacent entertainment complex, citing their "fundamentally different" visions for the project.

Forest City Ratner Cos. filed suit in state Supreme Court in Mineola late Thursday, claiming that Blumenfeld Development Group, of Syosset, had attempted to make "unilateral" changes to the $229 million plan without Forest City's approval and met with potential tenants without their knowledge. Forest City is asking the court to declare that the firms are not partners.

The suit claims that months of discord between the firms led to "delays and gridlock" in submitting necessary plans to the Town of Hempstead.

DocumentsRead the lawsuit

Blumenfeld's "unilateral changes to the site plan, efforts to take control over the project, and its otherwise divisive manner of dealing with key constituents" have caused the relationship between the firms to deteriorate, the suit said.

Blumenfeld's "actions have made clear" that Forest City "needs to move forward with the Nassau Coliseum redevelopment without [Blumenfeld Development Group]'s . . . continued interference," according to the suit.

Blumenfeld officials denied the suit's claims. They said they plan to file suit against Forest City next week, asking the court to enforce the companies' "partnership" and seeking an injunction preventing Ratner from moving ahead with the development without them.

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Blumenfeld attorney Ronald Rosenberg said the companies are "equal partners" on the project, citing private emails, public statements and language in the county's 2013 lease agreement with Forest City.

"We are partners," company chief executive Ed Blumenfeld said. "They don't seem to get that."

County officials said their lease agreement is with Ratner, not Blumenfeld.

Forest City officials said a memorandum of understanding signed in August represented the only formal agreement between the firms to redevelop the Coliseum. When that document expired in November, Ratner told Blumenfeld he would move forward without him, the suit said.

In a Feb. 25 letter, Blumenfeld told Ratner that his attempt to remove him from the development "not only damaged our partnership and the project, but my family's good name and excellent reputation."

It was unclear Friday what the dispute may mean for the project's schedule.

Long Island Events Center, the Forest City affiliate created for the Coliseum project, has said it plans to begin renovating the Coliseum in August and to break ground on the retail and entertainment complex before year's end.

County officials said if the project is delayed in court, there would be no financial penalty to the firm.

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Forest City officials said the entire project remains on schedule and site plans will be submitted to the town in the coming weeks.

Nassau County spokesman Brian Nevin said County Executive Edward Mangano has been assured by Forest City executive chairman Bruce Ratner "that any dispute will not affect the timeline" for the project.

Another Blumenfeld attorney, David Kaplan, said they "certainly hope that there will be no delay."

Blumenfeld and Forest City were among four companies that bid on the redevelopment of the Coliseum and its surrounding property in 2013.

After the county settled on Forest City and the Madison Square Garden Company as finalists, Blumenfeld signed onto Ratner's proposal, agreeing to develop the retail and restaurant components. Ratner said at the time that Blumenfeld had decades of experience with Long Island development and would help identify tenants.

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Rosenberg said Ratner has since "drastically scaled down the scope of the project to only the minimum required" by the lease agreement, depriving the county and its residents of millions in rental and tax revenue and the loss of jobs.

Forest City officials said the complex would be as much as 188,000 square feet -- the minimum space stipulated in the company's contract with Nassau. The plan, which could be later expanded, includes restaurants, a movie theater and a nightclub. No retail stores are planned.

Blumenfeld's plan includes about 300,000 square feet of retail and restaurants, with a 100,000-square-foot Bass Pro Shop, a Modell's sporting goods store, a Dave & Buster's restaurant, an indoor trampoline park and a movie theater.

"It became very clear from the start that we had completely different visions for the retail and Coliseum," said Ratner spokesman Ashley Cotton. "It's really about choosing to do something unique instead of something ordinary."

The lawsuit claims Blumenfeld also took an "overly aggressive posture" against Ratner's plan to bring a Memorial Sloan Kettering cancer treatment center to the redevelopment site. Sloan announced plans earlier this month to spend $140 million in private funds to build an outpatient treatment and research facility adjacent to the Nassau Coliseum.

Blumenfeld said he supports the project but raised concerns about how many parking spots the cancer center would use.

Forest City and Blumenfeld previously worked together on the East River Plaza, a big-box mall along the FDR Drive in East Harlem.