ZURICH (Reuters) - Swiss watchmaker Swatch Group said on Monday Tiffany & Co had served it with a 541.9 million-Swiss franc ($590 million)counterclaim in a legal dispute with the U.S. jeweler over a severed cooperation agreement.

Swatch Group, the world's largest watchmaker, said in September it had ended its alliance with Tiffany and would sue for damages.

The partnership, in which Swatch agreed to design and produce watches for Tiffany, was begun in late 2007. Swatch said its damages claim was for 3.8 billion francs.

($1=0.9190 Swiss francs)

(Reporting by Catherine Bosley; Editing by Greg Mahlich)