China has placed 1.7 million people under lockdown in central Anhui province, where authorities have reported nearly 300 new cases, in the latest of a string of outbreaks testing Beijing's no-tolerance approach to Covid-19.

The province reported 287 new infections on Monday, including 258 people who had no symptoms, according to China's National Health Commission, bringing the total cases found to just over 1,000.

Two counties in the province — Sixian and Lingbi — announced lockdowns last week, with more than 1.7 million residents only permitted to leave their homes if they are getting tested.

Footage from state broadcaster CCTV showed empty streets in Sixian over the weekend and people lining up for their sixth round of mass testing in recent days.

Provincial governor Wang Qingxian urged local authorities to "seize every minute and earnestly implement quick screening" as well as rapid quarantine and reporting of cases, in a statement published by the Anhui government on Monday.

Neighbouring Jiangsu province also reported 56 new local infections across four cities on Monday.

Strategy pitfalls

The country is the last major economy wedded to a zero-Covid strategy, responding to all cases with strict isolation orders and tough testing campaigns.

The outbreak in Anhui — where officials first found hundreds of cases last week — comes as the Chinese economy begins to rebound from a months-long lockdown in Shanghai and disruptive Covid restrictions in the capital Beijing.

While cases remain low relative to China's vast population, officials insist the zero-Covid policy is necessary to prevent a healthcare calamity, pointing to unevenly distributed medical resources and low vaccination rates among the elderly.

But the strategy has hammered the world's second-largest economy and heavy-handed enforcement has triggered rare protests in the country.

China's international isolation has also prompted some foreign businesses and families with the financial means to make exit plans.

National authorities announced a reduced quarantine requirement for international arrivals last month, rallying most Asian markets as investors hoped the move could provide a boost for Beijing's Covid-slumped economy.

But health official Lei Zhenglong has insisted the new quarantine policy was "absolutely not a loosening of (Covid) prevention and control".