All countries must work together to investigate the origin of the coronavirus that sparked the pandemic, the World Health Organization (WHO) said on Friday, a day after China rejected the proposed scope of a second phase.

WHO spokesman Tarik Jasarevic, asked about China's rejection, told a U.N. briefing in Geneva: "This is not about politics, it's not about a blame game.

"It is about basically a requirement we all have to try to understand how the pathogen came into the human population. In this sense, countries really have the responsibility to work together and to work with WHO in a spirit of partnership."