United States ambassador to China Gary Locke, who has repeatedly won the praise of Chinese for his frugal travelling habits, has again impressed after refusing to stay in a five-star hotel.

In a country where officials keenly show off their wealth, Locke's simple habits, like carrying his own luggage or flying economy class, are regularly reported by a media increasingly critical of their leaders' extravagance.

During a stay at China's resort island of Hainan last week, Locke, dubbed "the backpacker" by Chinese web users, turned down the five-star rooms of the Sofitel Hotel for less posh accommodations, the Global Times said.

Locke's move to a four-star hotel came as world leaders and policy-makers opted for the plush Sofitel during the Boao Forum, an elite conference which discusses global economic issues.

Locke's choice won immediate plaudits on Chinese microblogs.

This case "illustrates the lack of regulatory supervision of our officials when they travel on business trips which leads to a waste of public money," said Chuanyude Angle on Sina's Weibo microblog.

Sung Zude, a television presenter known for being particularly outspoken raised the possibility that Locke's choice of hotel was nothing but a marketing stunt.

But he added on his blog that Locke's behaviour, "so unique in China," was "giving officials a headache."

Last summer Locke, a former US commerce secretary, seduced the Chinese public with his "guy next door" attitude when he was photographed with his daughter carrying a backpack and queuing for coffee.

The picture was seen by millions of Chinese Internet users.