A senior Chinese official sparked contempt online Thursday after he compared the Sino-US relationship to a marriage -- although not a homosexual one.

At a high-level meeting in Washington between the world's two biggest economies, Vice Premier Wang Yang compared his relationship with US Treasury Secretary Jacob Lew to that of newlyweds.

"I know the United States allows same-sex marriage, but obviously I don't think myself and Jacob actually want this," he continued, according to China News Service.

The US and China should respect each other "like a husband and wife" and should "enhance mutual trust", he continued in a speech described by the state-run news agency as "unscripted" and "humorous".

Wang also said Beijing and Washington should "not divorce like Wendi Deng and Rupert Murdoch, or the price would be too high", comments which "sparked laughter" according to the China News Service report.

But such remarks would be considered out of place at any polite dinner table in China, and Wang's move away from the normally ultra-formal style of senior Chinese politicians was ridiculed in his home country.

"Embarrassing. I feel sick," said one poster on Sina Weibo, one of China's hugely popular Twitter-like microblogging sites.

"And this a Chinese vice minister?" said another.

Despite huge social and economic changes in recent years, China remains largely conservative, particularly among older generations.

"Disgraceful, is China the US's concubine now?" read one online comment. "What about our dignity?"