Two of the city’s leading landowners are suing a fellow titan of the local real estate scene in a clash brought on by the recent acquisition of a competing residential management company, according to a legal filing in state Supreme Court.

In what could be the first lawsuit against one of their partners in more than a decade, Arthur and William Lie Zeckendorf have filed a summons, which is among the first legal steps taken before filing a formal lawsuit, against Kent Swig, with whom they purchased Brown Harris Stevens, one of the city’s largest real estate brokerage firms, in 1995.

According to an attorney for the Zeckendorfs, Jamie Brickell, the dispute arose in early October when Mr. Swig bought a competing property brokerage firm, Helmsley-Spear, with his private real estate company, Swig Equities, and did not immediately inform the Zeckendorfs of the move.

“Acquiring a company that does residential management is in violation of the BHS agreement,” Mr. Brickell said.

“They’re not supposed to purchase competitive companies, period,” he added.

While it is understood that each partner has separate real estate businesses as well, the Brown Harris operating agreement specifically prohibits them from purchasing competitive companies, Mr. Brickell said.

Mr. Brickell said he hopes to meet today with Mr. Swig and his attorneys to discuss the claims and said he would prefer to settle the case out of court.

Mr. Swig refused to comment on the charges. A message left yesterday with his attorney, Robert Bodian, was not returned.