The RCMP says a Haitian woman complained to Haitian National Police that a Canadian police officer sexually and physically assaulted her.
Spokesman Vincenzo Pugliese, confirmed the UN is currently investigating the alleged incident.
The RCMP says the officer returned to Canada on his own without authorization from Canadian or UN authorities.
A spokespersonfor Canada's foreign affairs minister John Baird responded to the allegations in an email.
He said the government is taking the allegations very seriously, and said Canada would co-operate with any potential investigations.
More than 80 Canadian police officers are working with the UN mission in Haiti.