A Taiwan university has filed a patent infringement suit against Apple in a US court over the iPhone maker's Siri speech recognition system, which lets users place calls or perform other tasks with voice commands, and is seeking undisclosed damages.

Apple is also wrestling with Samsung Electronics in one of the biggest-ever technology patent trials as a lengthening list of foes big and small charges into legal battle with Apple over patents and trademarks for its popular mobile devices.

Earlier this month, Apple paid $US60 million to Proview Technology (Shenzhen) to end a protracted legal dispute over the iPad trademark in China.

Taiwan's National Cheng Kung University said on Monday it had launched a suit alleging that Apple's use of Siri in its iPhone and future versions of its iPad infringes two US patents it was granted in 2007 and 2010 that relate to voice-to-text technology.

The suit was filed in the United States District Court for the Eastern District of Texas, Marshall Division, on Friday, it said.

"We filed that lawsuit in the Texas court because it processes faster and its rulings are usually in favour of patent owners and the compensations are usually higher," said Yama Chen, legal manager of National Cheng Kung, in the southern Taiwan city of Tainan.

He declined to disclose the amount of compensation the university was seeking but said any calculation would be based on Apple's US sales of devices that use Siri.

An Apple representative in Asia could not immediately be reached for comment.

Chen said the university was also examining whether smartphone voice recognition systems used by Google and Microsoft have infringed its patents.

Two small Chinese companies have filed suits against Apple in China, with Jiangsu Xuebao charging trademark violations for the use of Snow Leopard as the name of its computer operating system and Zhi Zhen Internet Technology targeting the voice assistant functions used in Siri, Chinese media reports said in early July.

- Reuters