The group, the Writers Rights Alliance, petitioned Apple last year to stop electronic distribution of the writers' books and had earlier persuaded Baidu, China's largest search engine, to stop publishing their material on its Baidu Library product.

The writers are seeking 50 million yuan ($8 million) compensation from Apple, saying it was selling pirated versions of 95 books via its online store, Xinhua reported, without stating where the claim had been filed.

"As an IP holder ourselves, we understand the importance of protecting intellectual property, and when we receive complaints we respond promptly and appropriately," Apple spokeswoman Carolyn Wu said.

The Writers Rights Alliance could not be reached for comment. Foreign companies have complained for years about lax enforcement of intellectual property rules by China, and a growing number of Chinese copyright holders are now also pressing for better protection.

The lawsuit adds to Apple's list of problems in China.

The world's most valuable technology company has been embroiled in a long-running lawsuit with Chinese firm Proview Technology, which is fighting for control of the iPad trademark in China.

The unit of near-bankrupt Proview International Holdings has asked Chinese distributors to stop selling the iPad after Apple launched the latest version.

Apple is also battling allegations of poor working conditions among its army of low-cost suppliers in China.

Three workers at Foxconn Technology died in a blast last year when dust from polishing iPads ignited, and labour rights groups have said 18 workers at Foxconn sites killed themselves, or tried to, in 2010.

Apple has commissioned the non-profit Fair Labor Association to interview 35,000 workers at three of Foxconn's sprawling factories and prepare a report on working conditions. {ID:nL4E8E54NL]

• A Permanent Economic Emergency