Alberta's Energy Minister Marg McCuaig-Boyd has assured Albertans that the results of the investigation into the Nexen pipeline leak will be made public.

"Spills like this are unacceptable," she said at a news conference in Fort McMurray Friday.

The Alberta Energy Regulator is investigating the leak, which saw the release of five million litres of bitumen emulsion onto a right-of-way near Long Lake, south of Fort McMurray.

"We have confidence that the regulator is doing its job to conduct a timely and thorough investigation," she said. "Once the investigation is complete, it will be made public."

The AER revealed that the pipeline was never inspected before it was put into operation last year. Companies are only required to test pipelines every five years.

Minister thanks cleanup crews

McCuaig-Boyd also thanked the 130 workers cleaning up the spill, one of the biggest in the province's history, saying she was impressed with their efforts following a tour Friday morning.

McCuaig-Boyd and Environment Minister Shannon Phillips also met with members of the Fort McMurray First Nation, the Alberta Energy Regulator and Nexen.

Phillips said she was troubled by the lag between when the pipeline began to leak and when it was discovered, which may have been up to two weeks.

The leak was discovered last Wednesday by a contractor walking along the pipeline.

She said she found other aspects of the leak troubling, but wouldn't provide further comment as she believed the energy regulator needs space to do its work.

Nexen has apologized for the spill.