One of the nation's largest real estate firms attempted to raid Iowa Realty Co. Inc. before entering the Greater Des Moines market, then its local franchise operation filed a frivolous court case to gain an advantage, alleges a lawsuit filed Thursday in Polk County District Court.

Iowa Realty is in court with Keller Williams Realty Inc. and its local arm, Keller Williams Greater Realty Des Moines, not quite two months after the local company dismissed a lawsuit it filed shortly after entering the metro area market in March 2012 through a merger with Clive-based Burnett Realty.

Six years earlier, Keller Williams sought to raid Iowa Realty of its most productive real estate agents and to persuade them to open a franchise in Greater Des Moines, according to the Iowa Realty lawsuit.

When that effort failed on a broad scale, investors created Keller Williams Realty Greater Des Moines and merged with Burnett Realty. However, one Iowa Realty agent invested in the Keller Williams franchise before leaving Iowa Realty. Her daughter also left Iowa Realty for Keller Williams, but not before the women continued to attempt to persuade Iowa Realty agents to bolt the company and provided internal Iowa Realty documents to Keller Williams , the lawsuit alleges.

In June 2012, Keller Williams filed a lawsuit in an apparent attempt to force Iowa Realty to share commissions. That court case was dismissed in August. Keller Williams also filed complaints with the Des Moines Area Association of Realtors, all of which were dismissed, according to the lawsuit filed by Iowa Realty.

"For 14 months Iowa Realty has spent substantial time and money to defend against a meritless case, as well as endure relentless attacks on Iowa Realty's good reputation," Joan Johnson, senior vice president and general counsel for Iowa Realty, said in a statement.

Brian Wentz, CEO of Keller Williams Greater Des Moines, said that to "the extent allegations that our company or our agents have done anything wrong, it's patently untrue and we'll defend those claims vigorously."

Wentz also said Keller Williams' Greater Des Moines franchise has become the third largest real estate company in the metro area.