The city says it received the request from a group earlier this year and set aside the week of Oct. 14 - 20 for the designation.
Mayor Michael Fougere (foo-zhare) even signed a proclamation.
The mayor says he didn't realize that it was the Nationalist Party Of Canada that made the request.
Fougere says the city plans to cancel "European Heritage Week" in Regina, although the Nationalist Party is already celebrating the designation on its website.
Over the years Halifax, Victoria, Fredericton and other communities have made the same mistake. (CJME, The Canadian Press)