SHANGHAI: Shanghai authorities on Wednesday called for calm as worried citizens swamped online grocery platforms to stock up on food over fears of impending lockdowns in a city struggling to halt a Covid spike.

China is experiencing its worst Covid-19 outbreak since the start of the pandemic more than two years ago, with Shanghai posting record-high case counts as the highly transmissible Omicron variant frustrates authorities.

China’s biggest city on Wednesday reported 981 cases — all but four of them asymptomatic — a number that dwarfs any previous daily tally in the city and which is nearly one-fifth of the day’s national total.

Shanghai has responded to the outbreak with targeted residential lockdowns in areas with confirmed cases or close contacts.

There are growing public fears of more local lockdowns or stay-at-home orders for the entire city of roughly 25 million people.

Public concern has spiralled in the city in recent days and residents have taken to social media to air their frustrations.