Nokia will defend itself vigorously against Apple's confidential complaint to the US International Trade Commission (USITC) against Nokia, filed on Friday, the company said.
In a letter to USITC secretary Marilyn Abbott, Apple asked the commission to conduct an investigation under the US Tariff Act's intellectual property provisions "regarding certain mobile communications and computer devices and components thereof", citing Nokia as the respondent.
Apple was responding to a Nokia complaint filed with the USITC against Apple in December, alleging that Apple had violated at least seven Nokia patents in its iPhone smartphone as well as in portable music players and computers.
In October Nokia sued Apple in the federal court in Delaware, alleging that Apple's iPhone infringed Nokia patents for GSM, UMTS and wireless Lan standards.
Apple countersued, claiming that Nokia was infringing 13 Apple patents. "Other companies must compete with us by inventing their own technologies, not just by stealing ours," said Bruce Sewell, Apple's general counsel and senior vice-president.
Nokia said the seven patents in the December complaint relate to Nokia's "pioneering innovations that are now being used by Apple to create key features in its products in the area of user interface, as well as camera, antenna and power management technologies.
"These patented technologies are important to Nokia's success as they allow better user experience, lower manufacturing costs, smaller size and longer battery life for Nokia products," it said.
Nokia's general manager for patent licensing Paul Melin said the firm's litigation in Delaware was about Apple's attempt to free-ride on the back of Nokia investment in wireless standards. "The ITC case is about Apple's practice of building its business on Nokia's proprietary innovation," he said.
Although Nokia's smartphones outsell iPhones by five to one, Apple's profits from smartphone sales overshadow Nokia's.
A Nokia spokesman told Reuters at the weekend, "Nokia will study the [USITC] complaint when it is received and continue to defend itself vigorously. However, this does not alter the fact that Apple has failed to agree appropriate terms for using Nokia technology and has been seeking a free ride on Nokia's innovation since it shipped the first iPhone in 2007."