New York online advertising company 24/7 Media Inc. announced it filed a patent infringement lawsuit against competitor DoubleClick Inc. The suit, which was filed in U.S. District Court for the Southern District of New York, alleges that DoubleClick has infringed on 24/7 Media's U.S. Patent No. 6,026,368, which was awarded for creating an online system for providing advertising information to targeted viewers. The suit, which seeks monetary damages and an injunction, claims DoubleClick's DART ad serving system uses this patent without authorization. ``We have not yet seen the complaint,'' said Elizabeth Wang, VP-general counsel, DoubleClick. ``However, based on our initial review of the patent, we believe that any claim of infringement would be baseless. We will defend ourselves vigorously.'' DoubleClick filed its own patent-infringement suit against 24/7 Media's Sabela Media unit last fall, which pointed out that 24/7 received its patent in February. DoubleClick received its DART technology patentÃU.S. Patent No. 5,948,061Ãin September.