Several Chinese cities went on high Covid-19 alert as the Lunar New Year holiday travel season started on Monday, requiring travellers to report their trips days before their arrival, as the Omicron variant reached more areas including Beijing.

Authorities have warned the highly contagious Omicron adds to the increased risk of Covid-19 transmission as hundreds of millions of people travel around China for the Lunar New Year on Feb. 1.

Cities such as Luoyang in central China and Jieyang in the south said on Sunday travellers need to report to...