CALGARY - The future of the Energy East pipeline has been thrown into question after TransCanada Corp. announced it wants to suspend for now its application to build the $15.7-billion project.

In a statement Thursday, Calgary-based TransCanada (TSX:TRP) says it filed a letter to the National Energy Board asking for a 30-day suspension for the proposed the 4,500-kilometre pipeline which would carry crude from Alberta and Saskatchewan to refineries in Eastern Canada.

The company says it wants to study how the NEB's decision last month to consider the Energy East's contribution to upstream and downstream greenhouse gas emissions will affect "costs, schedules and viability."

TransCanada is calling the changes to the regulator process "significant," and warns that the entire project and related Eastern Mainline pipeline project could be cancelled.

The NEB decision was cheered by environmentalists but considered a setback by the oil industry.

It's another blow to the massive project after a review was derailed last year when members of the regulatory panel overseeing the NEB hearings resigned amid questions about a potential conflict of interest.