Apple is facing more legal problems over the iPhone after a court filing accusing the firm of infringing on an inventor's patent.

Romek Figa, a Massachusetts-based inventor, has filed a legal suit against Apple over its use of a caller ID function which identifies incoming callers based on their phone number.

Figa claims to have had a patent on the process since 1990. He approached Apple in July last year and suggested a fee for using the technology. The company refused and the inventor has now taken his case to court.

"Apple is actively engaged in acts of direct infringement of the '496 patent, " the suit reads.

"Apple's infringement has been and continues to be willful and deliberate. Apple will continue to engage in such acts unless enjoined by this court."

Figa is asking for a monetary award for damages and a sum equalling three times that figure because Apple knew that it was infringing on his intellectual property rights.