Shanghai has entered the largest ever lockdown since the beginning of the COVID-19 pandemic due to 3,500 cases of the disease, the South China Morning Post reported.

The administration closes the southern, eastern and western parts of the city to test citizens for the coronavirus. Shanghai's population of about 25 million has already been placed under strict quarantine.

Out of 3,500 cases of COVID-19, some of those infected carry the virus asymptomatically.