A Chinese city has locked down its 1.1 million residents after reports of new coronavirus cases as officials rushed to contain even small outbreaks just over four weeks before the Winter Olympics begin.

The curbs in the city of Yuzhou, in the central province of Henan, are similar to those imposed for nearly two weeks in the industrial hub of Xian, which has become China’s latest Covid-19 epicentre.

Yuzhou, 700km southwest of Beijing, has ordered all residents to remain indoors and not to leave town, the local Communist Party said in a statement late on Monday.

“So far, the source of the virus is unknown, the number of cases is unclear ... the virus control and prevention situation in our city is very severe,” authorities in Xuchang city, which has jurisdiction over Yuzhou, said on Tuesday.

“To curb and quash the epidemic within the shortest amount of time is a high-priority political task facing all officials and people in the city,” they said.

The greater Xuchang area reported two locally transmitted infections with confirmed clinical symptoms, and 18 local asymptomatic carriers for Monday, official data showed. It was not clear how many were in Yuzhou. Vehicles were banned from Yuzhou’s roads unless they have clearance from virus control authorities.