India's Sun Pharmaceutical Industries Ltd. (524715.BY) Wednesday said Pfizer Inc.'s (PFE) Wyeth Pharmaceuticals Inc. unit is claiming damages of $960 million in a patent dispute over a generic version of the U.S. company's Protonix heartburn drug.

A U.S. court had in 2010 turned down Sun Pharmaceutical's plea seeking to deem Pfizer's Protonix patent invalid. This had opened the way for damage claims against the generic producers of the drug--India's Sun Pharmaceutical and Israel's Teva Pharmaceutical Industries Ltd. (TEVA.TV).

Sun Pharma Wednesday said it has "sound reasons to disagree with these overstated claims of Wyeth."

The Indian generic drug maker said it will now provide its own assessment on the purported damages, following which the court will decide on whether there has been patent misuse and determine the appropriate level of damages.

Protonix was a top-selling drug for Wyeth, which was acquired by Pfizer in 2009. Wyeth and Nycomed--the company from which it licensed the Protonix patent--had filed patent-infringement suits against Teva and Sun Pharma in 2004, seeking to block their attempts to sell generic Protonix before patent protection expired in January 2011.

Sun Pharma and Teva had launched generic Protonix "at risk" but subsequently stopped sales of the drug.

-By Rumman Ahmed, Dow Jones Newswires; 91-9845104173; rumman.ahmed@dowjones.com