Chinese consumers have a voracious appetite for all things Apple, but the appealing gadgets and computers are also attracting increasing controversy.

Even as a high-profile lawsuit over rights to the iPad trademark in China continues in Guangzhou, Apple Inc now faces another intellectual property challenge - from Chinese writers who allege the US electronics giant enables illegal downloads of their books.

Last month the Beijing No 2 Intermediate People's Court agreed to hear a lawsuit against Apple brought by an alliance of 22 well-known writers who claim the company's App Store provides programs for download that include pirated copies of 95 books.

The group is asking for more than 11 million yuan ($1.7 million) in damages and plans to seek another 20 million yuan in compensation in another lawsuit, the alliance's founder Bei Zhicheng told local media.

Apple public relations spokeswoman Huang Yu'na said in an email to the media that "Apple understands the importance of protecting intellectual property rights".

She said the company will "respond properly and in a timely fashion" to the lawsuit, according to Xinhua News Agency.

The court is expected to begin hearing the case in the last half of the year, said Wang Guohua, an attorney for the alliance.

"I have five books on the App Store for reading with or without charges, but I did not authorize them," said Mai Jia, one of the writers in the alliance.

Apple usually deletes infringing applications about a month after receiving a letter of complaint, but provides no apology or compensation, China Central Television quoted a staff member at the alliance saying.

An Internet portal is usually free from liability if it deletes pirated material uploaded by a third party, but Apple could be held responsible because it charges a fee for downloads and keeps 30 percent for itself, China Nation Radio quoted intellectual property lawyer You Yunting saying.

Zhang Ping, a law professor at Peking University, noted that operators of a supermarket or a locale selling knockoffs such as the Silk Street market in Beijing are still liable for infringing goods sold there.

But Guangdong lawyer Zhao Hongbin cited a previous claim against online shopping site Taobao for providing links to infringing goods. Taobao was not held liable because the court found it had only an indirect interest, Zhao told Southern Metropolis Daily.

The newspaper cited an anonymous software developer saying the legality of all apps is hard to check.

He said that when offending developers submitted the apps, books included were likely legal, but after passing Apple's audit, pirated content might later be added unknown to Apple.

"Technically, it is hard to control," he said.

Zhang Hongbo, deputy director general of the China Written Works Copyright Society, said that there are 20 to 30 million Apple device users on the Chinese mainland, many of them white-collar professionals with strong purchasing power.

Because the market holds so much potential, free book downloads mean tremendous losses to writers and publishing houses, Zhang said.

Information from Apple shows that 550,000 apps have been supplied globally since the launch of its online store in July 2008.

Some 25 billion apps have since been downloaded, Apple announced early this month.