Covid-19 infections have risen across China this month after Beijing dismantled its zero-Covid policies, including regular PCR testing of its population.
The surge has triggered concern around the world and questions about Beijing's data reporting, with low official figures on cases and deaths despite some hospitals and morgues being overwhelmed. The US, South Korea, India, Italy, Japan and Taiwan have all imposed testing for travellers from China in response.
The UN health agency said it held talks with Chinese officials on Friday "to seek further information on the situation, and to offer WHO's expertise and further support".
It said officials from China's National Health Commission and the National Disease Control and Prevention Administration briefed the WHO on China's evolving strategy and actions on epidemiology, variant monitoring, vaccination, clinical care, communication and research and development.
"WHO again asked for regular sharing of specific and real-time data on the epidemiological situation — including more genetic sequencing data, data on disease impact including hospitalisations, intensive care unit admissions and deaths," it said.
It also asked for data on vaccinations delivered and vaccination status, especially in vulnerable people and those aged over 60.
"WHO reiterated the importance of vaccination and boosters to protect against severe disease and death for people at higher risk," the agency said.
"WHO called on China to strengthen viral sequencing, clinical management and impact assessment, and expressed willingness to provide support on these areas, as well as on risk communications on vaccination to counter hesitancy."
The UN agency said Chinese scientists were invited to engage more closely in WHO-led Covid-19 expert networks, and asked them to present detailed data at a virus evolution advisory group meeting on Tuesday.
"WHO stressed the importance of monitoring and the timely publication of data to help China and the global community to formulate accurate risk assessments and to inform effective responses," it said.
China said this month it would end mandatory quarantine for people arriving in the country and that it had abandoned strict measures to contain the virus.
The surge in cases in China comes almost exactly three years on since the first infections were recorded in the Chinese city of Wuhan in late 2019.
Since then, more than 650 million confirmed Covid-19 cases and more than 6.6 million deaths have been reported, although the UN health agency acknowledges this will be a vast undercount.
The search for the origins of the virus remains unresolved, with WHO Director-General Tedros Adhanom Ghebreyesus insisting that all hypotheses remain in the table, including the theory that the virus escaped from Wuhan's virology laboratories.
He has called on China to share data and conduct the studies requested by the WHO to better understand where the SARS-CoV-2 virus that causes Covid-19 disease sprang from.
With reporting from agencies