A group of 22 Chinese authors have filed a lawsuit against US technology giant Apple, claiming that its App Store sells unlicensed copies of their books and demanding a compensation of 50 million yuan (US$7.9 million).

The writers said Apple is selling pirated copies of 95 books on its online App Store.

The writers, including Han Han, He Ma and Nanpai Sanshu, established the Writers Rights Alliance to protect their rights. Last year, the alliance has petitioned Apple to stop electronic distribution of the writer's books.

The alliance has already sent a lawyer's letter to Apple and is waiting for the company's reply, said Bei Zhicheng, head of the alliance. According to the group, Apple takes a 30 percent cut from app sales on the platform.

The group also claimed that when the Californian company was notified about the pirated content, it was too slow to remove the products.

Public relations spokeswoman for Apple Huang Yu'na said in an email to media that Apple understands the importance of protecting intellectual property rights. The company will "respond properly and timely" to complaints.

The National Copyright Administration confirmed on Saturday that the App Store is suspected of piracy and copyright infringement, but it has to consult with other "relevant departments" to make a judgment.

Meanwhile, Apple and Chinese electronics firm Proview Shenzhen are still sparring in courts over the lengthy iPad trademark case, while the Chinese company is seeking to have iPad sales and exports blocked.

A Chinese court is still considering an appeal by Apple of an earlier ruling against its claim to the trademark.