In a terse statement, the spokesman for the UN Secretary General Ban Ki-Moon said the damages claim was "not receivable", under a convention that grants the United Nations immunity for its actions.

Families of the victims are demanding millions of dollars in compensation, accusing the UN of introducing the disease to Haiti.

The UN has never admitted responsibility, despite mounting evidence that the epidemic was caused by poor sanitation at a peacekeeping camp.

A lawyer for the cholera victims told the BBC that UN immunity could not mean impunity, and said the case would now be pursued in a national court.

The lawyer, Brian Concannon, said the victims' legal team would challenge the UN's right to immunity from Haitian courts, on the grounds that it hadn't established an alternative mechanism for dealing with accountability issues, as stipulated in its agreement with the government.

He also said lifting immunity would not challenge UN policy, which is protected by the convention, but its practice, such as how to test troops for disease and properly dispose of sewage.

There's evidence that infected Nepalese peacekeepers caused the epidemic by dumping untreated waste into a key river system, but the UN insists it's impossible to pinpoint blame definitively.

Late last year it launched an initiative to eliminate cholera in Haiti by investing in clean drinking water and sanitation systems, a move Mr Concannon said he considered an unofficial response to the victims' claims.