Apple has been accused by a company in Shanghai, China, of infringing a software patent used for the Siri voice-activated personal assistant feature found on the iPhone devices.

Zhizhen Network Technology claimed Apple violated its patent for a voice recognition software called "Xiao i", which the latter denied at a hearing in Shanghai No.1 Intermediate People's Court, the Shanghai Daily newspaper reported Thursday.

Apple said Zhizhen's accusation was unclear and lacked evidence, adding Siri did not violate the patent because it does not have a game server, which is one of the technical features of Xiao i.

But the Shanghai company said there was infringement if the operation modes of Siri and Xiao i are the same. It also claimed the infringement applied to all Apple devices that use Siri, including the iPhone 4S, iPhone 5 and iPad Mini.

"Apple has unveiled more products with the Siri application after we filed the lawsuit," said Yuan Yang, Zhizhen's lawyer. "We think all the above products infringed the patent right of Xiao i Robot voice recognition software."

According to an earlier Shanghai Daily report Wednesday, Zhizhen had filed a suit on June 21, 2012, requesting Apple to stop producing and selling products with Siri in China, but the hearing was delayed because the court decided to deliver the notice through diplomatic channels, as Apple is based in the United States.

Mei Li, a spokesperson from Zhizhen, said the company had been developing the Xiao i chat robot system since 2003. Zhizhen applied for patent rights for Xiao i in China in 2004 which came into effect in 2006. Siri, on the other hand, was developed in 2007, a year later, she noted.

Apple acquired Siri in 2010, and debuted the feature when it launched the iPhone 4S in 2011. Siri works by responding to a user's voice commands.

"We think Siri infringes our patent right in the word chat. We want them to stop it as everyone can see iPhones and iPads are widely sold in China," Mei said.

Zhizhen said it is not demanding compensation, but asking the court to confirm the patent right. Meanwhile Apple has applied to China's State Intellectual Property Office to demand that Xiao i's patent be invalidated. It asked the court to suspend the court pending this ruling, which the court rejected but granted another for both sides to find evidence, the report said.

A separate report by AFP Wednesday, however, quoted Si Weijiang, a lawyer representing Zhizhen, as saying: The company will ask Apple to stop manufacturing and selling products using its patent rights, once Apple's infringement is confirmed. We don't exclude the possibility of demanding compensation in the future."

According to Zhizhen, its Xiao i product has over 100 million users in China, and is widely used in many sectors including telecommunications, finance and e-commerce, AFP reported.

The dispute with Zhizhen comes after Apple ended another legal battle with a Chinese company. Last year, Apple paid US$60 million to Shenzhen's Proview Technology to settle a long-running trademark spat over the "iPad" name which both companies claimed ownership.

In July 2012, Apple also faced a Siri patent lawsuit filed in the U.S. after Taiwan's National Cheng Kung University claimed Siri speech recognition infringed on two of its U.S. patents.