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.

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.