The death toll in China’s coronavirus outbreak has risen to 25, with the number of confirmed cases also leaping to 830, the government said on Friday.

The National Health Commission said authorities were also examining 1,072 suspected cases of the virus that first emerged in central city of Wuhan.

The markedly higher numbers were released just hours after the World Health Organization (WHO) stopped short of declaring the situation to be a global health emergency.

WHO has said that the deadly virus outbreak is an emergency in China but has not yet become a global health emergency. It announced that it was “too early” to declare the outbreak of the novel coronavirus in China a public health emergency of international concern (PHEIC) while warning that the number of cases may increase as much about the virus remains unknown.

Meanwhile, China has effectively quarantined nearly 20 million people across Wuhan — the fifth largest city with a population of around 11 million people — and at least nine other cities in an unprecedented effort to contain the outbreak of the deadly new virus.

The government has also announced measures to curb its spread nationwide as hundreds of millions of people began travelling across the country this week for the Lunar New Year holiday.

The National Health Commission said the death toll was revised upward following eight new deaths on Thursday, and 259 new cases of the novel coronavirus (2019-nCoV) reported across the country.

Out of the total 830 confirmed cases, 177 were in serious condition, it added.

Thirty-four people have been “cured and discharged”.

The health authorities carried out medical follow-ups with 9,507 people who had been in close contact with the infected, with 8,420 of those still under observation.

Majority of the cases has been reported from Wuhan, the capital of Hubei province, where a seafood market that illegally sold wild animals has been identified as the epicentre of the outbreak.

Fearing that the epidemic may spread further, Chinese authorities in a late night notification, have asked residents not to leave the city unless necessary.

The coronavirus has caused alarm because of its similarity to SARS (Severe Acute Respiratory Syndrome), which killed nearly 650 people across mainland China and Hong Kong in 2002-2003.

Like SARS, it can be passed among people through the respiratory tract.

The symptoms of infection include fever, cough and breathing problems.

The first case of the new coronavirus was confirmed on December 31 in China, and it has since been detected in Japan, Hong Kong, Macau, South Korea, Taiwan, Thailand and the United States.