Differing cost estimates for Enbridge Inc.'s Northern Gateway oil pipeline to the West Coast from Alberta created confusion when the federal Joint Review Panel released its recommendation to proceed on Thursday.

Enbridge and most of the media have been using $6.5-billion for the capital cost of the 525,000-barrel-a-day pipeline for several months. The panel, in its report on the project, published a $7.9-billion figure.

So which one is right? According to Enbridge CEO Al Monaco, they both are.

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Mr. Monaco stressed that the discrepancy does not represent a big inflationary jump.

"There's the $6.5-billion. That's 2010 dollars, and that was a preliminary estimate. Now, as you spend money, you've got to finance that capital. There's interest cost that accumulates as you spend the money. That's what the $7.9-billion is," he told The Globe and Mail.

"So, one is pre-financing and one is after financing."

Meanwhile, with its conditional clearance in hand, it plans to update the costs in the next three months, he said.