BEIJING, Dec 22 (Reuters) - The Chinese city of Xian has ordered its 13 million residents to stay at home and urged them not to leave town unnecessarily as it struggles to contain rising COVID-19 cases under Beijing"s guideline that flare-ups must be curbed as quickly as possible. Xian, in China"s northwest, has reported more than 140 domestically transmitted infections with confirmed symptoms since Dec. 12 in its latest cluster caused by the Delta variant of the coronavirus. A handful of cities have detected cases linked to the Xian outbreak, including one from the capital Beijing. Despite that, the reported numbers are tiny compared with many fresh outbreaks seen around the rest of the world, including some driven by the Omicron strain of the virus that emerged last month. The Xian government, however, pledged to clamp down on movement by its residents, as Beijing has signalled it will not tolerate a significant spread of infection. The city has yet to impose a harsh lockdown like that seen in early 2020 in the city of Wuhan, but urged residents not to leave town unless they are tested for COVID-19 before departure and get clearance from employers or community-level authorities. Local authorities had dissuaded more than 7,000 people from trying to leave, state broadcaster CCTV said, without elaborating. Starting Thursday, only one person in each Xian household can go out for necessary shopping every two days, while other family members must stay home unless they have essential jobs, Xian government official Zhang Fenghu told a news briefing. The city also suspended dining at restaurants as well as large conferences and exhibitions, shut down non-essential businesses and told employees to work remotely. China has reported several Omicron cases among international travellers and one locally transmitted infection.