Greenpeace activists occupy a smoke stack at the Shell Scotford upgrader expansion site near Fort Saskatchewan, Alberta, Canada.
Activists from Canada, France, Brazil and Australia scaled the under-construction upgrader to lock down to the structures early this morning. Two have been detained.
Upgraders are part of the energy-intensive process used to produce dirty oil from tar-like bitumen. This is the third Greenpeace action against tar sands operations in the last three weeks.