Enbridge was forced to close down the Athabasca pipeline this week following a spill at the Elk Point oil pumping station in Alberta.
In a statement late on Tuesday Canadian pipeline operator Enbridge confirmed an estimated 1400 barrels of oil were released on Monday, with the failure of a flange gasket in the pumping station believed to be the cause of the spill.
Enbridge said the Athabasca pipeline was shut down immediately on Monday once the leak at the pumping station was detected.
It added the spill was largely contained within the pumping station site and the area was secured and clean-up operations began immediately.
The pipeline was restarted later on Monday and was running normally but the company was forced to close the line again on Tuesday on the order of the Energy Resources Conservation Board (ERCB) while an investigation into the spill is carried out.
Enbridge said it was currently in talks with the ERCB in order to determine when the line can be re-opened.
The 540 kilometre Athabasca pipeline carries oil from a number of oilsands projects in Northern Alberta to the Battle River Terminal, near Hardisty, Alberta.