Apple Inc may face another lawsuit in China as a Shanghai-based company claimed that the US giant's voice technology Siri has infringed on a patent involving its own personal assistant software.

Shanghai Zhizhen Network Technology Co Ltd, the developer of the voice technology called Xiao i Robot, has sued Apple in China, asserting that Siri has violated one of its patents.

The firm's chairman Yuan Hui said Zhizhen sent a legal notice to Apple in May, but received no response.

Zhizhen then filed the suit on June 21 and a Shanghai court announced on June 26 that it will hear the case "quite soon", according to Yuan.

The move came only days after Apple Inc paid $60 million to Proview Technology (Shenzhen) to end a protracted legal dispute over the iPad trademark in China.

Zhizhen's patent covers "a type of instant messaging chat robot system", according to the database of the country's State Intellectual Property Office. It was filed on Aug 13, 2004, and got approved on Feb 15, 2006.

"We have 100 million users in China, and many companies are using our product," Yuan told China Daily on Friday.

In comparison, Siri Inc, essentially a start-up company Apple acquired in 2010, started producing the mobile virtual assistant in 2007.

It allows users to ask questions about finding consumer goods, services or destinations once the program is activated on Apple's smart devices.

Siri became available in China starting early this year, when the iPhone 4S was officially launched in the country. In June, Apple launched Siri services in Mandarin and Cantonese.

Yuan said the Xiao i Robot can communicate through voice, and can answer users' questions while also holding simple conversations.

The software is available on mobile operating systems such as iOS and Android, and has been running on online chat tool Windows Live Messenger for a long time.

Its clients include China's three major telecom operators, computer-maker Lenovo Group Ltd, government agencies as well as major banks and financial institutions, the company's website showed.

For instance, Fetion, the instant messaging software developed by China Mobile Communications Corp, has embraced the Xiao i Robot technology. Once adding Xiao i Robot's account as a friend, users will be virtually chatting with the robot.

At this point, the suit does not make a specific request for compensation.

"Our only demand is that Apple stop infringing on our patent and cover the court costs," Yuan said.

Apple did not respond to a request for comment on Friday.

The case is the latest legal hurdle Apple has had to clear in China.

After settling with Proview Technology Shenzhen Co Ltd for $60 million over the use of their iPad trademark in China, the company was hit earlier this week with a suit from Jiangsu Xuebao Daily Chemical Co Ltd for allegedly infringing its "Snow Leopard" trademark, because a version of the Mac OS X also uses the Snow Leopard name in Chinese.

Siri and Xiao i Robot have overlapping functions such as online chatting and information inquiries, but Siri outperforms Xiao i Robot in terms of the commercial application of its technology, said Geng Yan, a smart phone specialist at CCID Consulting Co Ltd.

"Siri is closely linked with social networking sites and business databases. For example, it works with Yelp, a popular dining-review site abroad, to provide intelligent suggestions. There are definitely business dimensions behind such cooperation," Geng said.

To determine whether Siri has violated Zhizhen's intellectual property rights, Geng said it is necessary to delve into the source code which Xiao i Robot applied for its patent, and compare it with that of Siri's.

He added that the settlement with Proview could be seen as a benchmark for what Apple is willing to pay for clean access to a trademark, but that would also embolden trademark trolls looking to make a quick buck off the world's richest company.

But Yuan insisted that his company does not ride the coattails of previous lawsuits against Apple in China, as it has been planning to sue the Apple for long.

"People feel that China has no innovation that companies here just copy. But in fact, we are a leader in our field, and we have created our own innovation," Yuan said.

hewei@chinadaily.com.cn