HELSINKI, Finland — Nokia Corp., the world's largest mobile phone maker, said yesterday that it has asked the United States to ban imports of chipsets made by Qualcomm Inc. along with phones and other products made with those chipsets.

In asking the U.S. International Trade Commission to start an investigation, Nokia claimed that Qualcomm has engaged in unfair trade practices by infringing on Nokia's patents. A 2001 licensing agreement between the two companies, which have been embroiled in a dispute over royalty fees, expired in April.

Nokia's complaint is part of a multinational legal battle with Qualcomm, the world's No. 2 chipmaker for mobile phones. The announcement comes two months after the same commission banned U.S. imports of new cell phones made with Qualcomm semiconductors because the chips violate a patent held by rival chipmaker Broadcom Corp.

Qualcomm declined to comment on specifics of Nokia's complaint but said it was part of a broader licensing dispute. Nokia is seeking to pay less for rights to Qualcomm technology than it did under the expired 2001 agreement, which has not been renewed.

Smith Brittingham, a Washington, D.C., patent attorney, said Nokia may be striking back for a complaint that Qualcomm filed before the ITC in June 2006, seeking an import ban on Nokia products that it said violated its patents. A hearing in that case is scheduled Sept. 10.

The legal skirmish dates to October 2005, when Nokia and five other companies complained to the European Union about San Diego-based Qualcomm's business practices. The commission is considering the complaint.