Apple has filed an antitrust complaint against Motorola Mobility with the European Commission (EC), regarding the proper use of patents.

According to a 10-K filing made by Motorola Mobility to the US Securities and Exchange Commission, Apple sent a letter to the EC alleging that Motorola has violated a promise to licence essential industry-standard patents on fair and reasonable – or FRAND – terms.

FRAND terms require companies holding industry-standard patents to license them under conditions that don’t harm competition or aren’t seen as too expensive to rival firms. “Apple’s complaint seeks the Commission’s intervention with respect to standards-essential patents,” the filing said.

The European Commission last week approved the US$12.5 billion sale of Motorola Mobility to Google, along with the US Department of Justice. It was previously reported that Google promised to use Motorola patents fairly, sending letters signed to this effect to the relevant authorities, including the European Telecommunications Standards Institute (ETSI).

Apple and Motorola have been engaging in legal action regarding the use of patents in the US and Germany. The most recent ruling on a case between the two companies saw Motorola win a permanent injunction against Apple’s iCloud service in Germany, which could lead to a ban on the sale of iPhones and iPads in the country. In January, Motorola submitted a lawsuit in a Florida federal court accusing Apple of infringing six of its technology patents.