(Reuters) - Watson Pharmaceuticals Inc said on Friday it has applied for U.S. approval to market a generic version of Velcade, a treatment for multiple myeloma made by Takeda Pharmaceutical Co.

Takeda's Millennium unit filed a lawsuit last week against Watson's Actavis unit, seeking to prevent Actavis from selling generic Velcade prior to the expiration of certain U.S. patents.

Drug companies that file lawsuits against generic manufacturers which challenge their patents are typically granted a protection period of up to 30 months from the date of the generic drugmaker's filing for approval of its own drug.

Velcade, which generated sales of $740 million in the 12 months ended October, is one of the leading treatments for multiple myeloma.

(Reporting By Toni Clarke; editing by John Wallace)