Citizens of China and Japan overwhelmingly support President Barack Obama to win a second term, according to an AFP-Ipsos poll which suggests Mitt Romney's tough talk on the Asian powers could have dented his image.

The US elections may be a toss-up at home but the survey carried out by Ipsos Hong Kong found a whopping 86 percent of Japanese back the Democrat incumbent compared to only 12.3 percent for Republican party candidate Romney.

Chinese respondents were less emphatic, but still a hefty 63 percent said they wanted Obama to serve out another four years, according to the online poll conducted in September and October.

Analysts said Obama's record on the economy and security had buttressed his standing in the East, while Romney's outspoken comments on Beijing's alleged currency manipulation and Japan's economic decline may have lost him some friends.

"Asia wants Obama to win the election overall, but China has more supporters of Romney than Japan," Ipsos Hong Kong associate director Andrew Lam said.

"It is possible that Romney's strong stand on currency and trade, as well as his plan to have a stronger military capability in the Pacific, has led the Chinese to believe it is better to stay with the status quo.

"For Japan, Romney's low popularity is possibly linked to his earlier public comment about Japan being an economy in decline. Japanese have strong national pride, and could react negatively toward this kind of public remark."

The Chinese are around three times more likely to approve of Romney despite his more hawkish stance on trade and military spending, according to the AFP-Ipsos survey which will be publicly released on Monday.

Romney's popularity was highest among older Chinese and in less developed "Tier Two" cities, inland population centres which have not industrialised at the pace of the more economically liberal special economic zones such as Shanghai.

International relations expert Chen Qi, of China's Tsinghua University, said some Chinese held the Republican party in high regard based on its history of engagement with Beijing going back to president Richard Nixon's 1972 visit.

But he said many other Chinese did not look favourably on Romney's background as a wealthy capitalist.

"Many people feel that Obama looks after the bottom level of society, with his policies such as medical reform, and a lot of Chinese people support that... There is some suspicion of rich businessmen entering politics," Chen said.

Romney has repeatedly vowed to brand Beijing a "currency manipulator" on his first day in office, as a way to address China's huge trade surplus with the United States.

"They're taking jobs, and we've been looking the other way for too long," he said on the campaign trail last month.

Critics in the United States and other developed economies accuse China of keeping its currency deliberately low to flood the world with exports of inexpensive goods, devastating manufacturing industries elsewhere.

The Obama administration has repeatedly urged Beijing to let the yuan appreciate, but has stopped short of declaring China a currency manipulator -- a designation that could trigger sanctions and perhaps an all-out trade war.

The AFP-Ipsos survey showed that most Japanese (81.8 percent) and Chinese (58.3 percent) thought Obama would be the best US president for Asian economic growth, rejecting Romney's claims to be the stronger economic manager.

Asked which candidate would be better for peace and security in Asia, 85.3 percent of Japanese and 56.3 percent of Chinese said Obama.

Takehiko Yamamoto, professor of international politics at Tokyo's Waseda University, said Obama's efforts to end the wars in Afghanistan and Iraq were popular in Japan.

"The Bush administration took a kind of coercive approach to Japan in mustering support for the Japan-US alliance when it dealt with Afghanistan and Iraq. But Obama has not been so forcible," he told AFP in Tokyo.

Obama's so-called "pivot" to Asia has been a key strategy of his administration's foreign policy, a move that China has eyed with suspicion but other Asian states have broadly welcomed as a balance to Beijing's influence.

Despite the high stakes involved, the poll showed many more Chinese (47.7 percent) are indifferent to the US election outcome than Japanese (30.3 percent).

Analysts said that with a once-a-decade leadership transition due to take place in Beijing shortly after the US vote, this was not surprising. There was also a sense of disappointment after the excitement of Obama's 2008 victory.

"The election is the most important to the Japanese, possibly because the US has been their most important long-term ally diplomatically and militarily," said Lam.

"With their rising political and economic power, the Chinese may regard themselves as less reliant on any single nation including the US, thus the indifference."

The poll, which surveyed around 1,000 people in each country, has a margin of error of five percent.