Chinese bloggers and the media speculated Monday about whether the new US ambassador's Chinese roots would help Sino-US ties -- and nicknamed him "the backpacker" for his frugal travelling habits.

Gary Locke, formerly US commerce secretary, arrived in Beijing at the weekend carrying his own luggage and travelling in a regular car, with little of the ceremony that usually surrounds Chinese dignitaries abroad.

"Our own officials have got used to a luxury lifestyle," lamented one user of the Sina Weibo microblogging service in response to Locke's relaxed arrival, while the state Xinhua news agency dubbed him the US "backpacker".

Locke, the first Chinese American to hold the job, succeeds Jon Huntsman, who resigned to run for the Republican presidential nomination.

A column in the official China Daily newspaper said there were hopes Locke's ancestry would "help him be a bridge between China and the United States and between the two peoples".

"However, we should not pin too many hopes on him adopting a more pro-China approach than his predecessors," said the commentary, written by Tao Wenzhao, a scholar at the Centre for US-China Relations at Beijing's Tsinghua University.

Tao reminded readers that Locke would "work to serve the US national interests", in comments echoed online and in other newspapers amid excitement over the 61-year-old's China roots.

"Luo Jiahui (Locke's Chinese name) needs to prove to Americans that he will not be influenced by his Chinese lineage," one netizen said on Sina Weibo, China's most popular microblogging site.

"A lot of people understand that he will represent US interests, but... many Chinese people still have a fantasy about him."

Locke -- a third generation Chinese American whose grandfather emigrated to the US state of Washington -- was quick to point out his allegiance to the United States over the weekend.

"I am both humbled and honoured to stand here before you as a child of Chinese immigrants representing America, the land of my birth, and the American values my family holds dear," he told reporters.

Locke takes over at a time of fraught US-China relations, with tensions escalated by a range of disputes including Beijing's export-driven economic policies, growing military spending and human rights record.

On Sunday, Locke told journalists Washington was "committed to getting our fiscal house in order", addressing rising Chinese concerns over US economic woes that led to an unprecedented downgrade of the nation's top-notch credit rating.

"We note that over the last several days more people are buying US Treasuries," he said.

"So it's a clear indication that investment in the United States is safe, secure, and that the economy, while having its challenges, is still strong, and that investment in the United States is to be promoted."

Beijing has launched a barrage of criticism at the United States over the debt crisis, with state media savaging the country over what they call its "addiction to debt", in a series of unusually critical articles.

China is the biggest foreign holder of US debt, with holdings of $1.2 trillion, but analysts say it cannot conduct any large-scale selling of dollar assets without diminishing the value of its remaining holdings.

In a comment piece on Monday, Xinhua hinted at the scale of the task facing the new US envoy.

"A picture of a backpacker on the Internet attracted much attention from the Chinese people. Sunday afternoon, the backpacker appeared in front of the media as the new US ambassador," it said.

"One thing for sure is that his mission will be much heavier than the bag he carried on the way to China."