World Health Organization (WHO) experts are preparing a proposal on the next studies to be carried out into the origins of the virus that causes COVID-19, a spokeswoman said on Friday.

The United States called on Thursday for the WHO to carry out a second phase of its investigation into the origins, with independent experts given full access to original data and samples in China. Britain made a similar appeal.

WHO spokeswoman Fadela Chaib told a U.N. briefing on Friday that experts would prepare a proposal for WHO director-general Tedros Adhanom Ghebreyesus, but that there was no set timeline. Earlier this week WHO's top emergency expert Mike Ryan said that talks with member states would continue in coming weeks.