Ambrose Property Group said Wednesday it declined a $6 million offer from the city of Indianapolis to buy the former General Motors stamping plant site, the two sides apparently far apart in what the property is worth.

Ambrose founder and CEO Aasif Bade said in a written statement that he believes the property because of its development value is worth more than $65 million.

The offer and the developer's subsequent rejection are the latest steps toward a date in court unless some compromise is reached between two former partners whose $1.4 billion redevelopment plan would have filled a hole in the city's urban core.

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The city wants to buy the land through a voluntarily sale by Ambrose or by force through eminent domain after Ambrose backed out of the plan last month. Ambrose wants to find another buyer for the site and claims the city is violating the project agreement by pursuing ownership under eminent domain.

"If the City believes that $6 million is the true value of the property, the City should rescind its unlawful threat and compete with other buyers in the free market," Bade said.

Documents from the Marion County assessor's office indicate that Ambrose bought the land from the Revitalizing Auto Communities Environmental Response (or Racer) Trust in a group sale of four parcels for $3 million. Racer was formed to clean up and sell former General Motors Corp. properties around the country after the automaker's 2009 bankruptcy.

The city's purchase offer was made Wednesday during a meeting between the developer and the city's corporation counsel.

"Ambrose’s continued posturing, and its characterization of today’s meeting, are disappointing," a statement from the city's Office of Corporation Counsel said Wednesday. "We nevertheless remain optimistic that we can move forward with productive conversations about the future of this critical piece of property."

The city's corporation counsel did not respond to requests asking for confirmation of the amount of the city's offer.

Ambrose planned to build a $1.4 billion mixed-use development called Waterside on 103 acres that formerly held the stamping plant.

According to the project agreement with city, Ambrose initially projected the development to cost about $471 million, with the first phase costing about $92.5 million. Indianapolis officials agreed to contribute $26.7 million for phase 1 infrastructure, but Ambrose sought tens of millions of dollars more in public subsidies as project cost estimates tripled.

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The company and the city aimed for the development to be transformative and to extend the boundaries of Downtown Indianapolis west of the White River south of the Indianapolis Zoo. The plan called for multifamily high-rises, offices, and retail and greens space.

But in late September, the project collapsed. The developer abruptly announced plans to sell its mixed-use and office properties, including the former GM site, as it shifted its business to e-commerce and industrial development.

After news broke that Ambrose sold roughly 12 acres of the property to the Indianapolis Zoo, city officials moved to buy the land in an effort to control how development occurs there. The city issued Ambrose an ultimatum: Voluntarily negotiate a purchase price, or risk losing the property through eminent domain.

Ambrose has accused the city of committing title slander and breach of contract, insisting that the active project agreement with the city prevents the governmental body from seizing the land by force.

More on Waterside:Indianapolis threatens to seize former GM stamping plant property

The developer said the city's actions have prevented any sale of the property from occurring, resulting in additional losses of $65 to $100 million.

When asked to explain the calculation behind those figures, the company in a statement to IndyStar said Ambrose has been unable to pursue specific real estate transactions and other opportunities because of comments made by city officials.

The transactions, spokeswoman Mali Jeffers said, were worth $30 million at a minimum, adding that lost business opportunities continue to grow.

Ambrose's property value figures are based on both third party appraisals and discussions with potential buyers, she said.

Ambrose on Tuesday filed a notice of tort claims formally announcing its intention to sue the city as required by state law.

Contact IndyStar reporter Alexandria Burris at aburris@gannett.com. Follow her on Twitter: @allyburris.