Motorola has sued Apple for allegedly violating 18 of its patents relating to wireless email, antenna design and other technologies used in the company's iPhone and iPod touch devices.
The complaint, filed with the International Trade Commission and US district courts in Florida and Illinois, alleges that Motorola engaged in lengthy negotiations with Apple but was forced to file a lawsuit after Apple refused to pay licensing fees for the relevant technologies.
Wednesday's lawsuit came amid a flurry of legal actions among smartphone makers over alleged patent violations. Last week, Microsoft sued Motorola, while Nokia and Apple both have lawsuits pending against each other. Apple is also pursuing legal action against Taiwanese phone manufacturer HTC.