The United Nations secretary-general is to call for an independent commission to study whether UN peacekeepers unwittingly caused a cholera outbreak that has killed more than 2,400 people in Haiti.
UN officials initially dismissed speculation about the involvement of peacekeepers.
The announcement indicates that concern about the epidemic's origin has now reached the highest levels of the global organisation.
"We are urging and we are calling for what we could call an international panel," UN peacekeeping chief Alain Le Roy said at a news conference at UN headquarters in New York.
"We are in discussions with (the UN World Health Organisation) to find the best experts to be in a panel to be completely independent."
Mr Le Roy said details about the commission would be announced today by Secretary-General Ban Ki-moon and cholera experts and other scientists will have full access to UN data and the suspected military base.
"They will make their report to make sure the truth will be known," Mr Le Roy said.
Soon after the cholera outbreak became evident in October, Haitians began questioning whether it started at a UN base in Meille, outside the central plateau town of Mirebalais and upriver from where hundreds were falling ill. Speculation pointed to recently arrived peacekeepers from Nepal, a south Asia nation where cholera is endemic. UN officials rejected any idea the base was involved, saying its sanitation was air-tight.
WHO and the US Centres for Disease Control and Prevention said at the time that it was unlikely the origin would ever be known, and that pinning it down was not a priority.
Then international reporters uncovered that not only were there sanitation problems at the base, but that the UN mission was quietly taking samples from behind the post to test for cholera.
When the CDC determined the strain in Haiti matched one in south Asia, cholera and global health experts said there was enough circumstantial evidence to warrant an investigation.