In court papers filed Tuesday in the Delaware Court of Chancery, Kroger said Albertsons disregarded the companies’ merger agreement and worked secretly with a partner, C&S Wholesalers, to try to force Kroger to divest more stores to C&S.

Kroger Co. on Tuesday filed a countersuit in its dispute with Albertstons Cos. over a failed $25 billion merger between the two grocery behemoths.

Kroger Co. is fighting back against a lawsuit brought by Albertsons Cos. over its failed $24.6 billion takeover of the rival grocery chain, escalating a dispute that began after US antitrust enforcers succeeded in blocking the deal last year.