Video | UN now investigating 'rumour' that troops caused cholera in Haiti

It began as a rumour that farmers saw waste from a UN base flow into a river within days of the talk – and Haitians who asked about it were called either political or paranoid, while foreigners were accused of playing “the blame game.”

The World Health Organization also went on record saying the question was simply "not a priority."

But a week after anti-UN riots and inquiries from health experts, top U.N. representatives in Haiti said they are taking the allegations very seriously.

"It is very important to know if it came from (the Nepalese base) or not, and someday I hope we will find out," UN envoy Edmond Mulet was reported as saying. The answer would have implications for UN peacekeeping missions around the world, he said.

What is certain is that the answer would seriously affect the relationship between the UN and Haiti: If its peacekeepers had misled local health authorities, it could lose credibility for tasks such as helping oversee next week's election.

 The incident could also affect the job of thousands UN humanitarian workers who nevertheless work separately from the peacekeepers.