Canada Post workers in Regina have walked off the job.
Canadian Union of Postal Workers (CUPW) went on strike at 6 a.m. local time on Thursday.
Rotating strike action is also taking place at a number of other locations across the country.
Workers in other locations in Saskatchewan walked off the job on Oct. 30, but returned to work the following day.
The latest rotating strike action comes as the union’s overtime ban becomes effective across the country.
On Wednesday, CUPW said the overtime ban means postal workers can refuse to work beyond their normal eight-hour days.
The union and the postal service have been unable to reach new collective agreements for two bargaining units after 10 months of negotiations.
Canada Post has said it provided “significant” offers to its employees, including wage hikes.
CUPW said the wage offers from Canada Post fall far below expected cost-of-living increases.
Labour Minister Patty Hajdu appointed Morton Mitchnick, a former chairman of the Ontario Labour Relations Board, to help the two parties resolve their differences.
– With files from the Canadian Press