The World Health Organization and China's National Health Commission will continue collaboration on containing the outbreak of the novel coronavirus, including studying the severity and transmissibility of the virus and for China to share biological material with WHO to contribute to the development of vaccines for the virus, it said.

The WHO will also send international experts to visit China as soon as possible to work with Chinese counterparts on increasing an understanding of the outbreak to guide global response efforts, it said in a statement on Tuesday.

The statement came after the meeting between President Xi Jinping and Tedros Adhanom Ghebreyesus, director-general of the WHO, at the Great Hall of the People in Beijing on Tuesday. 

"We appreciate the seriousness with which China is taking this outbreak, especially the commitment from top leadership, and the transparency they have demonstrated, including sharing data and the genetic sequence of the virus," the WHO statement said. "The WHO will keep working side-by-side with China and all other countries to protect health and keep people safe."

The number of reported confirmed cases of the virus rose to nearly 6,000 on the Chinese mainland as of Tuesday midnight, China's National Health Commission said. Some experts in China have predicted the peak of the outbreak will appear in about 10 days.

The current understanding of 2019-nCoV, the novel coronavirus, remains limited, and the source of the outbreak and the extent to which it has spread in China are not yet known, according to the statement. 

"Both the WHO and China noted that the number of cases being reported, including those outside China, is deeply concerning," the statement said. "Better understanding of the transmissibility and severity of the virus is urgently required to guide other countries on appropriate response measures."

Existing studies show most cases of the virus reported to date have been milder, with about 20 percent of all confirmed cases experiencing severe illness, it said.