Hong Kong leader Carrie Lam today declared a virus emergency in the Asian financial hub, announcing a package of measures to limit the city's links with mainland China.

Schools, now on Lunar New Year holidays, would remain shut until February 17, while inbound and outbound flights and high-speed rail trips between Hong Kong and Wuhan would be halted.

Lam said all official visits to the mainland and official Lunar New Year celebrations would be scrapped immediately.

She also said she had sought the assistance from China's State Council to ensure mask supplies were adequate.

The city's health authorities have confirmed five coronavirus cases, all linked to Wuhan, where the virus first appeared, with a further 122 people being treated as suspected of having the disease.