Swiss watchmaker Swatch Group says it is being sued for 541.9 million Swiss francs ($589 million) by its former business partner Tiffany & Co. over a contract dispute.
Swatch says the New York-based jeweler is striking back after the Swiss group last year claimed 3.8 billion in damages from Tiffany.
The watchmaker accuses Tiffany of obstructing a joint venture the companies created in 2007.
Swatch said in a statement Monday that Tiffany's counterclaim "has no factual or legal basis and will be vigorously contested."
Tiffany couldn't immediately be reached for comment.
Shares in Swatch were down 0.4 percent at 73.70 francs ($80.07) on the Zurich exchange.