The city of 13 million, which entered its fourth day of lockdown, detected 155 domestically transmitted cases with confirmed symptoms for Saturday, up from 75 a day earlier, official data showed on Sunday.
That drove the national daily count to 158, the highest since China managed to contain a nationwide outbreak in early 2020.
Xi’an, with 485 local symptomatic cases reported for the 9-25 December period, has imposed heavy-handed measures to rein in the outbreak, in line with Beijing’s policy that any flare-up should be contained as soon as possible.
The city managed to quickly detect those cases through three rounds of mass testing, He Wenquan, a Xi’an official, told a press conference on Sunday, adding that high case numbers could persist into the next couple of days.
“In order to quickly screen out the infected groups of people, after an analysis by experts, we will step up control measures in key areas, especially places with greater risk level,” said He.
The local government also announced that it would launch a city-wide disinfection campaign from 18:00 local time, urging residents to shut the windows and bring clothes or other items inside from their balconies.
Residents may not leave town without approval from employers or local authorities and multiple rounds of mass testing were conducted to identify cases.
The city has announced no infections caused by the Omicron variant, although Chinese authorities have reported a handful of Omicron infections among international travellers and in southern China.
Including imported cases, mainland China confirmed 206 new cases on 25 December, up from 140 a day earlier.
No new deaths were reported, leaving the cumulative death toll at 4,636. Mainland China had 101,077 confirmed cases as of 25 December.