Some Shell service stations in southern Ontario are running out of gas. ((Darryl Dyck/Canadian Press))

Shell Canada is blaming the delayed reopening of an oil refinery in Sarnia for a gas shortage in parts of southern Ontario, including Toronto and Windsor.

A handful of Shell stations in Toronto have run out of regular gas because of delivery problems.

Some stations in Windsor are also affected.

A spokesman for the company says maintenance work at the Shell refinery in Sarnia took a week longer than expected — and that has led to delivery problems to Shell stations across southern Ontario.

CBC News contacted 25 Shell service stations across Toronto and found several reported being completely out of gas.

Some said they had run out of the lower grades, and at least one said it was selling higher grade gas for the lower price.