A worker (left) wearing protective gear disinfects chairs in a public area at the Beijing Capital Airport in Beijing on March 5, 2020. (GREG BAKER / AFP)

BEIJING - Chinese health authorities said Friday that China must not relax its vigilance or lower the level of work in epidemic prevention and control as the number of imported cases of COVID-19 increases.

The Chinese mainland reported 17 new confirmed cases of COVID-19 on Thursday outside Hubei province, the epicenter of the outbreak, said Mi Feng, an official with the National Health Commission, at a press conference. 

Of them, 16 cases, including 11 in Gansu, four in Beijing and one in Shanghai, were imported from outside the mainland, said Mi.

ALSO READ: Mainland reports 17 new COVID-19 cases outside Hubei

"We should continue to deepen international cooperation, share information and experience with the World Health Organization and relevant countries in a timely manner, and jointly fight the epidemic," Mi added.

By Thursday, the mainland had seen a total of 36 imported COVID-19 cases, according to the commission.

READ MORE: Authorities on alert for imported infections