Generics producer Actavis has sued the U.S. Food and Drug Administration, challenging its decision to award exclusive rights to Israel's Teva to sell a generic version of Pfizer's blockbuster painkiller Celebrex.

The move follows a similar lawsuit announced earlier by another generics producer Mylan.

On Apr. 17, Teva signed a deal that allows it to launch a generic version of Celebrex in December. The agreement came after a U.S. court in March invalidated a patent extending Pfizer's marketing exclusivity for the drug to Dec. 2, 2015.

Celebrex's basic chemical patent is now set to expire next month, as planned. Pfizer, however, has said it will continue to defend the patent extending its exclusivity.

The FDA usually grants 180 days of marketing exclusivity to drugmakers who are first to file for generic approvals. Teva, the world's largest generic producer said it believed it was the first to file for an approval for Celebrex.

The Pfizer drug, which is used to treat arthritis pain and inflammation, generated about $2.92 billion in sales in 2013, according to the company's annual regulatory filing.