GENEVA/BRUSSELS — Leaders of 23 countries and the World Health Organization (WHO) on Tuesday backed drawing up an international treaty that would help deal with future health emergencies like the coronavirus pandemic by tightening rules on sharing information.

The idea of such a treaty, also aimed at ensuring universal and equitable access to vaccines, medicines, and diagnostics for pandemics, was floated by the chairman of European Union leaders, Charles Michel, last November.

WHO Director-General Tedros Adhanom Ghebreyesus has endorsed the proposal, but formal negotiations have not begun, diplomats say.

Mr. Tedros told a news conference on Tuesday that a treaty would tackle gaps exposed by the coronavirus disease 2019 (COVID-19) pandemic. A draft resolution on negotiations could be presented to the WHO’s 194 member states at their annual meeting in May, he said.

The WHO has been criticized for its handling of the COVID-19 pandemic and was accused by the administration of US President Donald J. Trump of helping China shield the extent of its outbreak, which the agency denies.

A joint WHO-China study on the virus’s origins said it had probably been transmitted from bats to humans through another animal and that a lab leak was “extremely unlikely” as a cause. Data was withheld from WHO experts who went to China to research its origins, Mr. Tedros said.

The treaty proposal got the formal backing of the leaders of Fiji, Portugal, Romania, Britain, Rwanda, Kenya, France, Germany, Greece, Korea, Chile, Costa Rica, Albania, South Africa, Trinidad and Tobago, the Netherlands, Tunisia, Senegal, Spain, Norway, Serbia, Indonesia, Ukraine and the WHO itself.

“There will be other pandemics and other major health emergencies. No single government or multilateral agency can address this threat alone,” the leaders wrote in a joint opinion piece in major newspapers.

“We believe that nations should work together towards a new international treaty for pandemic preparedness and response.”

The leaders of China and the United States did not sign the piece, but Mr. Tedros said both powers had reacted positively to the proposal, and all states would be represented in talks.

White House spokeswoman Jan Psaki, speaking later to a regular press briefing in Washington, said: “We do have some concerns primarily about the timing on launching into negotiations for a new treaty right now.”

Negotiations could divert attention away from substantive issues regarding the pandemic response and future preparedness, although the Biden administration remained open to international collaboration, she added. — Reuters