The Chinese city of Xi'an, where 13 million residents are currently confined to their homes, announced tightened restrictions on Sunday as the country recorded its biggest Covid-19 infection numbers in 21 months, according to AFP.

China has stuck to a “zero-Covid” strategy involving tight border restrictions, lengthy quarantines and targeted lockdowns.

Authorities have been especially vigilant in recent months to avoid an outbreak before February's Beijing Winter Olympics, but there have been sporadic flare-ups.

But on Sunday, the country reported 206 new Covid infections — the highest daily number since March 2020.

“In the coming days, a number of cases are still likely to be detected,” Xi'an official He Wenquan warned, calling on the city's population not to panic.