Facebook was sued by Kickflip, which does business as Gambit, over claims the social-networking company broke antitrust laws in the virtual-currency market.

Gambit was the leading virtual currency and payment- processing provider to software developers that published games on Facebook and other social networks. Facebook’s decision in 2009 to offer its own services to developers destroyed a “vibrant and competitive market,” lawyers for Kickflip said in court papers made public yesterday in federal court in Wilmington, Del.