On the heels of a recent settlement of trade dispute with a Chinese firm, Apple Inc faced 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, 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 Mr Yuan Hui said Zhizhen sent a legal notice to Apple in May, but received no response, state run China Daily reported today.

Zhizhen then filed the suit on June 21 and a Shanghai court announced on June 26 that it will hear the case “quite soon’’, Mr Yuan said.

The development comes within days of Apple paying $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 August 13, 2004, and got approved on February 15, 2006.

“We have 100 million users in China, and many companies are using our product,” Mr Yuan told the Daily.

In comparison, Siri Inc, essentially a start-up company acquired by Apple in 2010, started producing the mobile virtual assistant in 2007. It helps users find consumer goods, services or destinations once the programme 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.