Officials say they are still not sure what caused an explosion and fire at Regina's Co-op refinery last week.
An external investigation was launched last week, but progress has been slow, as investigators are facing safety concerns.
Refinery officials aren't providing an update on the conditions of the two injured people who remain in hospital. They say a total of 36 people were hurt and 13 were taken to hospital.
About 1,200 contract workers at the refinery have been off the job since the incident, but most are expected to return to work soon.
Despite rumors to the contrary, officials at the refinery say there have been no layoffs so far.
Gasoline levels at the refinery are expected return to normal by Monday, but diesel production will remain down by about 20 per cent until May 2012.
