The United States' ambassador to China, Nicholas Burns, said on Thursday he expects Beijing's "zero Covid" policy to persist into early 2023, and that US businesses were reluctant to invest in the country until restrictions ease.

The re-emergence of infections in China's capital Beijing has raised new concerns about the outlook for the world's second-largest economy, which had recently emerged from a long lockdown that shook global supply chains in its most populous city and commercial hub, Shanghai.

"I think we're going to have to live with this for a long time," Burns told an online Brookings Institution event.

"My own assumption is that we'll see the continuation of 'zero Covid' probably into the beginning months of 2023. That's what the Chinese government is signalling," Burns said, referring to China's policy of seeking to stamp out each cluster of new cases, often with strict lockdowns and mass testing.

"I think there's a hesitancy to invest in future obligations until they can see the end of this," Burns said of US companies.

Analysts say the Chinese government's official GDP growth target of around 5.5% for this year will be hard to achieve without doing away with the strategy.

Burns criticised Beijing for censoring on Chinese social media Secretary of State Antony Blinken's May speech on US policy toward China, in which he said Washington expected Beijing to adhere to international rules.

"We put the speech on Weibo, and WeChat. And it was censored in about two and a half hours. Just taken away," Burns said, adding that the embassy reposted it days later and it was again removed.

Burns also said some assessments within China's government that the United States is in decline and is therefore becoming more aggressive toward China was not accurate and an "excuse".

"I think what's changed is the newly aggressive behaviour of the Chinese government ... over the last five to 10 years. And you've seen a counter-reaction to that," he said.

- Reuters