The principal Chicago investors in the SugarHouse Casino are asserting that Philadelphia partners with a minority stake are trying to squeeze financial concessions out of them and disrupt a refinancing deal.

Casino operators Neil G. Bluhm and Gregory Carlin said a legal feud that landed in Delaware Chancery Court is all about money.

They are responding to a complaint filed April 8 by the Philadelphia group, led by lawyer Richard A. Sprague and auto magnate Robert M. Potamkin.

In a filing Monday, Bluhm and Carlin said the local investors have demanded that the Chicago partners reduce from 20 percent to 12.5 percent the annual return on their senior preferred partnership interest.

When Bluhm and Carlin refused, they said the plaintiff - RPRS Gaming L.P. - "escalated its disruptive behavior" and filed the lawsuit.

Charles Hardy, a spokesman for Sprague, had no comment on the filing by Bluhm and Carlin. Carlin, the chief executive officer of SugarHouse, also declined further comment.

The Chicago partners have invested $150 million in cash in the casino project, located on Delaware Avenue on 22 acres on the boundary of Northern Liberties and Fishtown.

The Philadelphia partners have invested about $2.5 million in the venture, according to the court filing by Bluhm and Carlin.

In their complaint, the Philadelphia investors argued that they were being marginalized in decisions concerning the casino's future. The lawsuit claimed that a refinancing deal would limit additional borrowing and force a scaling back of a proposed expansion.

But Bluhm and Carlin said that was false. Construction plans for the next stage of development will not "result in a material decrease in the scope of the SugarHouse facility," the filing said.

SugarHouse opened its doors in September 2010 with 48,000 square feet of gaming space and parking for 1,465 cars. The casino partners told gaming regulators it would add a 10-story parking garage and double the gaming floor in the next phase of construction.

Bluhm and Carlin said the timing of the lawsuit "was no coincidence." They said it was an attempt to "scuttle the financing and force defendants to accept plaintiff's demand."

They also said the litigation threatened the "good working relationship" between the partnership, the Pennsylvania Gaming Control Board, and the City of Philadelphia by "painting a false portrait" of efforts to develop and expand the SugarHouse Casino.