Xi'an, which has been placed under lockdown, was responsible for 155 the 158 local COVID-19 cases China reported today ©Getty Images

Daily COVID-19 cases in China have hit a 21-month high, fewer than 40 days before the Winter Olympics are due to open in capital Beijing.

The Chinese Government reports 206 new coronavirus cases were detected yesterday, with 158 local cases - reflecting the largest figure for a 24-hour period since the first half of 2020.

Xi'an, a city under lockdown because of an escalating coronavirus outbreak, was responsible for 155 of these local cases.

The figure for Friday (December 24), announced yesterday, was 75 cases.

Xi'an is a roughly 1,000 kilometres from Beijing and has a population of 13 million.

It is the capital of landlocked province Shaanxi and home to the Terracotta Army sculptures, but is not due to play any direct role in the hosting of the Winter Olympics and Paralympics.

China has introduced more stringent COVID-19 restrictions in response to the emergence of the Omicron variant and immediate lead-up to Beijing 2022, including people from areas deemed high- and medium-risk needing to take nucleic acid tests before being allowed to travel to Beijing.

Six people were arrested in Beijing today for breaking coronavirus rules by coming to Beijing without taking tests, the state-run Global Times reports.

Olympic curling competition begins on February 2 ©Getty Images
Olympic curling competition begins on February 2 ©Getty Images

The Beijing 2022 Winter Olympics are set to take place from February 4 to 20, with the Winter Paralympics following from March 4 to 13.

All participants will exist within a "closed-loop management system", using only designated transport to move between approved venues.

Those who are fully vaccinated will not need to isolate for 21 days before entering the closed loop.

Overseas spectators have been banned because of the pandemic, but organisers hope to have domestic fans in attendance.

The pandemic has been one of the defining topics of the build-up to Beijing 2022, along with China's record on human rights and a United States-led diplomatic boycott on such grounds.

The National Hockey League is no longer releasing its players - considered the best men's ice hockey athletes in the world - for Beijing 2022, because of COVID-19 disruption.