Providing China with a heads up about the rules is part of a broader bid by the Biden administration to stabilise relations with Beijing.

The world's fourth-most populous country has recorded more than 6.7 million cases overall, with 160,583 fatalities.

Some places have been taken aback by the scale of China's outbreak and expressed scepticism over Beijing's Covid statistics.

Beijing plans to roll out what will be one of its biggest fiscal incentive packages over five years, mainly as subsidies and tax credits to bolster semiconductor production and research activities at home, sources say.

Strict limits on workplaces and gatherings are no more, with employees lingering outside workplaces and public transport teeming with commuters eager for normalcy after two years of containment.

In a special session of parliament to discuss the protest, the most violent in decades in the normally peaceful city, Ardern promised things would change, but gave no timeframe for easing curbs.

The quasi-emergency measures, as they are called, permit governors to limit mobility and business activities, by shortening the operating hours of bars and restaurants, and barring sales of alcohol.

The measures will mean around a third of England's population cannot travel or meet other households for Christmas.