China is taking steps to avert a potential outbreak of the Zika virus after the World Health Organization declared the mosquito-borne virus an international public health emergency.

The virus has been linked to thousands of birth defects in Brazil, but no travel or trade restrictions have been imposed so far.

A news release from the WHO China on Tuesday evening described the virus as "an extraordinary event" that looks set to constitute a public health risk to other countries through the international spread of disease.