Morneau said there'd be no fiscal impact of the plan - suggesting he doesn't expect to make or lose money on the deal.
The Canadian government said on Tuesday that it would buy a pipeline that has been the focus of widespread protests by environmentalists and some Indigenous groups, putting the government squarely on the side of the country's oil industry.
Shares of Calgary-based Kinder Morgan Canada, a unit of the Houston-based parent, surged as much as 9 per cent after the announcement, and were down 28 cents, or 1.69 percent, to $16.31 at 12:27 p.m.in Toronto. The expansion had been estimated at $7.4 billion.
May said Indigenous rights were not being respected in regards to the permits issued to twin the existing pipeline. "At the appropriate time, Canada will work with investors to transfer the project and related assets to a new owner or owners, in a way that ensures the project's construction and operation will proceed in a manner that protects the public interest", the government said on Tuesday.
Buying the pipeline outright had become increasingly likely after Prime Minister Justin Trudeau first pledged only to backstop it. Trudeau is gambling billions of Canadian taxpayer dollars on an oil project that will never be built - a project that Kinder Morgan itself has indicated is "untenable" and that faces more than a dozen lawsuits, crumbling economics, and a growing resistance movement that is spreading around the world.
When the sale is finished, Canada will continue construction on its own, with plans to eventually sell it all in the future once market conditions improve.
Kinder Canada Chief Executive Officer Steven Kean said on a conference call the company hasn't yet decided how it will use the proceeds from the sale and it will consider options including acquisitions and stock buybacks.
More than 200 people, including two members of Parliament, have been arrested already at Kinder Morgan's oil tanker and terminal site in Burnaby, British Columbia. "The government was under tremendous political pressure to get this deal done".