Two Aon Corp. units have sued several former executives and their new employer, Alliant Insurance Services Inc., alleging breach of contract, conspiracy and other charges in what Aon calls a “mass defection” of Aon employees and clients. In a chancery suit filed June 15 in Cook County Circuit Court in Chicago, Aon Risk Services Cos. Inc. and Aon Risk Insurance Services West Inc. alleged that the former executives violated their employment agreements with Aon. The group includes Peter Arkley, who resigned as chairman and CEO of Aon's construction services group earlier this week to head Alliant's construction practice. Aon holds that the former executives conspired with Newport Beach, California-based Alliant to solicit at least 40 other employees of Aon's construction services group to quit Aon and join Alliant, using “confidential and proprietary employee information such as Aon salaries, benefits and other employee information.” More than 40 Aon construction group employees have left Aon, the Chicago-based brokerage alleged. In its suit, Aon seeks unspecified economic and punitive damages. It also seeks injunctions to forbid the former executives from competing for Aon's construction business for two years following the termination of their employment, from soliciting Aon employees for the same period of time and from disclosing any of Aon's confidential and trade secret information. “The complaint speaks for itself,” said a spokesman for Aon. A spokeswoman for Alliant declined to comment. Filed by Mark A. Hofmann of Business Insurance, a sister publication of Workforce Management. To comment, e-mail email@example.com. Stay informed and connected. Get human resources news and HR features via Workforce Management's Twitter feed or RSS feeds for mobile devices and news readers.