The lawsuit, filed in Ontario Superior Court, claims BP did not properly measure the shipments received at its south-western Ontario plant through an Enbridge pipeline.

That caused Enbridge to miss about C$109 million worth of BP gas shipped to the plant during a five-year period, plus levies on the deliveries, the lawsuit says.

"[Gas]was therefore passing through the 'offline' meter without detection and without being measured and accounted for," says the lawsuit.

"The