World Health Organization chief Tedros Adhanom Ghebreyesus said on Wednesday that 80% of China's coronavirus cases are in the central Hubei province, and that not all provinces have been affected.

He said there were 24,363 confirmed cases in China and 490 deaths. The last 24-hour period of monitoring saw the most cases in a single day, he said.

Some 99% of all the cases worldwide are in China, he said.