Apple faced a Shanghai court yesterday, accused by a Chinese firm of copying software used for the "Siri" personal assistant on its iPhones.
Shanghai's Zhizhen Network Technology claims Apple infringed its patent for voice-recognition software, and the two companies have been summoned to present evidence at a pre-trial hearing, representatives of the Zhizhen said.
Chief executive Tim Cook said in January that he expected China to surpass the United States as Apple's largest market but the relationship had sometimes been troubled.
The latest legal challenge comes after Apple last year paid US$60 million to computer maker Shenzhen Proview Technology to settle a long-running dispute over the "iPad" trademark, whose ownership was claimed by both companies.
Chinese state media have also attacked Apple in recent days, with the People's Daily urging consumers in a commentary to "strike away Apple's unparalleled arrogance" for alleged double standards in customer service and returns policies.
Apple has denied those accusations in media statements.
Zhizhen said it patented its "Xiao i Robot" software in 2004, while Apple's Siri, which made its debut with the release of the iPhone 4S in 2011, was first developed in 2007.
Siri, described by Apple as an "intelligent personal assistant", responds to a user's commands. Zhizhen's product operates in a similar way and works on Apple's iOS system and its rival Android.
Zhizhen claims it has more than 100 million users in China, according to a statement.
"The company will ask Apple to stop manufacturing and selling products using its patent rights once Apple's infringement is confirmed," Si Weijiang , a lawyer for Zhizhen, said. "We don't exclude the possibility of demanding compensation in the future."
The full case is scheduled to be heard in July, according to a Zhizhen spokeswoman.