Unifor members have set up a blockade around a Co-op card lock at the intersection of Highways 13 and 39 near Weyburn.
Unifor said its members set them up around 4 a.m. today (Mon) and are allowing people to leave the site but only allowing employees in.
Co-op refinery workers have been locked out since December 5th with pension plans the main issue.
The workers have since locked out Co-op managers from their Regina facilities, blocked a Regina card lock and picketed in front of the Federated Cooperative Limited headquarters in Saskatoon.