Amazon's Kindle 3G e-reader is being snapped up on China's grey market as it has an extra special advantage for customers -- it automatically leaps the so-called "Great Firewall" of state web censorship.

Sites such as Facebook and Twitter, which are blocked by the Beijing authorities, can be accessed without interference by the Kindle's Internet browsing function, the South China Morning Post reported Monday.

Amazon says it is not able to ship the Kindle to mainland China or offer content in the country, which has the world's largest Internet community at more than 420 million web users, the Post reported.

But a seller in Beijing told the paper he slipped them into China a few at a time after having them delivered to an address outside the mainland. He has sold 300 in the past month.

AFP found dozens of Kindles available on web auction site Taobao, China's answer to eBay, with prices ranging from a special offer of 700 yuan (105 dollars) to 5,000 yuan.

Several Chinese bloggers are recommending the device, according to the paper, largely due to the fact it can "scale the wall automatically".

"I still can't believe it. I casually tried getting to Twitter, and what a surprise, I got there," the paper quoted a mainland blogger as saying.

"And then I quickly tried Facebook, and it perfectly presented itself. Am I dreaming? No, I pinched myself and it hurt."

The 3G Kindle uses global system mobile (GSM) communication technology, which gives WiFi coverage in more than 100 countries, including China. The WiFi-only Kindle would rely on a local Internet connection.

Professor Lawrence Yeung Kwan, of the University of Hong Kong's electrical and electronic engineering department, told the paper that mainland Internet patrols might have overlooked the gadget.

"Every Kindle device is pre-registered to a personal account, so every user's information is clear," he said.

"In addition, Kindle has a book-buying focus, so the censors may think these connections are relatively safe."

The Kindle has its own network, called Amazon Whispernet, to provide wireless coverage via AT&T's 3G data network in the US and partner networks in the rest of the world.

A 3G wireless coverage map on Amazon's website includes numerous Chinese cities, suggesting its 3G link involves a Chinese carrier, the paper said.