Imperva said it will “vigorously contest” a patent infringement lawsuit filed by rival company F5 Networks, alleging that Imperva’s products make use of F5’s patented web application security technology.

Washington-based F5 filed the patent infringement suit last Tuesday in U.S. District Court in Seattle. According to the complaint, Imperva infringed on F5’s patent, titled “Method and System for Extracting Application Protocol Characteristics,” which details methods and systems for defining a set of allowable actions regarding a network application.

The patent was granted by the U.S. Patent and Trademark Office in October 2001, according to the court filing. F5 claims that Imperva’s line of Secure Sphere products make use of its patented protected inventions, resulting in “substantial and irrefutable injury to F5 and its rights.”

Imperva denied F5’s claims.

“A few years ago, F5 began to sell its web application firewall,” Imperva said in a statement sent to SCMagazineUS.com on Tuesday. “Few bought it, choosing instead Imperva’s superior product. Unable to compete on the merits, F5 now reverts to litigation.”

Imperva said it respects the intellectual property rights of others and does not use or need F5’s technology. In addition, Imperva called F5’s patent “old” and said it is actually from 1999.

“Imperva believes this lawsuit is baseless and expects that when the facts are revealed, Imperva will prevail,” the statement continued. “F5 is using a legal strategy to compensate for inadequate sales and product development.”

Meanwhile, F5 is seeking a preliminary and permanent injunction to prohibit Imperva from making, using or selling any product that infringes on its patent. In addition, F5 is seeking payment from Imperva to compensate for damages the infringement has caused.

F5 defended its lawsuit, according to a brief statement sent to SCMagazineUS.com.

“F5 thinks it is appropriate to take reasonable measures to defend our intellectual property rights,” the statement said. “However, it is our current policy not to comment on pending litigation.”

A spokeswoman at the U.S. District Court in Seattle said no court date has currently been set.