The United Nations secretary-general plans to call for an independent commission to study whether U.N. peacekeepers caused a cholera outbreak that has killed more than 2,400 people in Haiti, an official said on Wednesday.

U.N. 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 organization.

“We are urging and we are calling for what we could call an international panel,” U.N. peacekeeping chief Alain Le Roy said at a news conference at U.N. headquarters in New York. “We are in discussions with (the U.N. World Health Organization) to find the best experts to be in a panel to be completely independent.”

Le Roy said details about the commission would be announced Friday by Secretary-General Ban Ki-moon. He said cholera experts and other scientists will have full access to U.N. data and the suspected military base.

“They will make their report to make sure the truth will be known,” Le Roy said.

Soon after the cholera outbreak became evident in October, Haitians began questioning whether it started at a U.N. 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.

U.N. officials rejected any idea the base was involved, saying its sanitation was air-tight.

WHO and the U.S. 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 the Associated Press found not only sanitation problems at the base, but that the U.N. 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 now enough circumstantial evidence implicating the likely unwitting Nepalese soldiers to warrant an aggressive investigation.

The experts have also said there are important scientific reasons to trace the origin of the outbreak, including learning how the disease spreads, how it can best be combated and what danger countries around Haiti could face in the coming months and years.

Many think the U.N. mission’s reticence to seriously address the allegations in public helped fuel anti-peacekeeper riots that broke out across the country last month.

This outbreak, which experts estimate could affect more than 600,000 people in impoverished Haiti, involves the first confirmed cases of cholera in Haiti since WHO records began in the mid-20th century. Suspected outbreaks of a different strain of cholera might have occurred in Haiti more than a century ago.

The current outbreak has spread to the neighbouring Dominican Republic and isolated cases have been found in the United States.

French epidemiologist Renaud Piarroux argues that “no other hypothesis” from the Nepalese being the origin could explain his findings that cases of the diarrheal disease first appeared near the U.N. base in Haiti’s rural centre, far from shipping ports and the area affected by the Jan. 12 earthquake.

But his findings were laid out in an unpublished, somewhat informal paper and are not universally accepted by scientists. Alternate hypotheses include that the disease was introduced by environmental factors, or had been dormant in Haiti’s soil.

Dr. David Sack, an epidemiologist at Johns Hopkins University, has said that weather patterns and cholera bacteria present in the Gulf of Mexico could also have caused the outbreak.

However, a team led by researchers from Harvard Medical School said this month in the New England Journal of Medicine that the disease was likely carried to Haiti by human activity and that it was indeed a South Asian strain which does not match cholera found elsewhere in Latin America.

At the Wednesday news conference, Le Roy said its investigations have not found the presence of cholera in its soldiers or at the base. But most people infected with cholera don’t show symptoms. The AP also found last month that the environmental testing was done at a Santo Domingo hospital with ties to the U.N. mission that likely lacked the special expertise epidemiologists said testing for cholera requires.

The proposed panel is promised to be much more comprehensive. The head of the U.N. Stabilization Mission in Haiti told AP last month that a definitive finding on the origin of cholera would impact peacekeeping missions around the world.

A separate U.N. team of water, sanitation and hygiene experts was already sent to Haiti in recent weeks to review all sanitation systems in place at the mission’s military, police and civilian installations, sources familiar with the review said on condition of anonymity because they were not authorized to discuss it with journalists.

Le Roy said the peacekeepers will “redouble our efforts” to ensure its bases worldwide have the best sanitation and health standards possible.