Authorities have all but shut down Wuhan, a city of 11 million and a major transport hub, as the death toll from the novel coronavirus outbreak surged past 800 in mainland China, overtaking global deaths during the 2002-2003 SARS epidemic.

The total number of coronavirus infections in China has risen to more than 37,000.

The coronavirus is thought to have originated in a seafood market in Wuhan - in northern China's Hubei province - that reportedly sold exotic animals for consumption, similar to the outbreak of SARS (severe acute respiratory syndrome). The virus is believed to have jumped from an animal to a human host.

The World Health Organization (WHO) on Sunday said the number of cases being reported daily in China appeared to be stabilising.

WHO's representative in Beijing, Gauden Galea, also said the "unprecedented" move to lock down Wuhan was "a very important indication of the commitment to contain the epidemic in the place where it is most concentrated", adding that such a directive was beyond the organisation's guidelines.

Lying on the banks of the mighty Yangtze River, flood-prone Wuhan measures 8,500 square kilometres (3,300 square miles), five times the size of Greater London, and includes rural areas as well as a sprawling conurbation.