CALGARY -- Costs for the long-delayed Keystone XL pipeline will likely balloon from US$5.4 billion to as much as US$10 billion, TransCanada Corp. confirmed Friday, as the project marked its sixth year in regulatory limbo.

CEO Russ Girling told the Wall Street Journal that the price tag could rise to a "number that gets you into the high single digits to a 10 number."

Company spokesman Shawn Howard confirmed the remarks.

"It is worth noting that increased project costs mean higher costs for refiners and consumers -- and those costs will likely be passed on to all of us as consumers," he added.

TransCanada (TSX:TRP) marked Friday what it called an "unfortunate milestone" for Keystone XL -- six years precisely since it applied for a U.S. permit to build the pipeline.

Keystone XL would link 830,000 barrels per day of mostly oilsands crude to an existing network that feeds into the lucrative U.S. Gulf Coast refining market.

Environmental concerns over the project range from a potential spill's impact on drinking water to the enabling of further oilsands development and its accompanying increase in greenhouse gas emissions.

Backers of the project say it would create construction jobs and displace crude imports to the U.S. from unfriendly regimes.

"Our goal is to have more oil moving through pipelines which are safer, produce fewer emissions and provide safe, secure and reliable supplies of oil to American refineries," said TransCanada president of development Alex Pourbaix.

Meanwhile, Reuters reported this week that U.S. hedge funds are eyeing a restructuring of TransCanada.

TransCanada, commenting on "significant trading activity" in its shares, said Friday it's expected to generate significant cash flow, earnings and dividend growth in its current form.

"With its commercially secured $38 billion capital program and ongoing growth in its three core businesses, the company is well positioned to create significant shareholder value," it said.

"Since 2000, TransCanada has delivered a 16 per cent annualized return to its shareholders including an average increase in dividends of seven per cent per annum."

Speaking to reporters on the sidelines of the Global Business Forum in Banff, Alta., TransCanada's former CEO, Hal Kvisle, said a break-up of TransCanada would be "wild speculation."

Kvisle, now Talisman Energy Inc.'s CEO, said TransCanada's portfolio today "makes a ton of sense."

"The market wants yield, they want reliable companies that pay strong dividends and they want strong management teams and TransCanada's got all of that."

Phil Adams, an analyst at independent corporate bond research firm Gimme Credit, said TransCanada should stay as-is.

"We agree with management that a strong balance sheet is critical for tackling an enormous list of growth projects," he wrote in a report.