The decision came after "a joint strategic and economic review" concluded that the project might struggle to be profitable long term.

"Since 2010, market conditions have changed significantly, challenging the economics of the Voyageur upgrader project," said Suncor chief executive Steve Williams.

"This decision is in line with our commitment to capital discipline and our stated plan to allocate capital with priority given to developing higher-return growth projects and accelerating the return of cash to shareholders through dividends and share buybacks."

Doubts