An explosion on a natural gas pipeline south of Winnipeg comes at a time when its owner, TransCanada Corp., is seeking to assure the public that proposed new oil pipelines to the east and south will be safe.

One $12-billion proposal called Energy East would see a portion of its cross-Canada natural gas mainline converted to ship oil from Alberta to Eastern Canada.

Environmental Defence's Adam Scott, who has been campaigning against Energy East, says the blast over the weekend shows that oil and gas pipelines are inherently risky to communities.

TransCanada is also awaiting a U.S. permit to build its controversial, $5.4-billion Keystone XL oil pipeline to U.S. markets and is expecting a final environmental report from the State Department within weeks.

NextGen Climate Group — led by U.S. billionaire Tom Steyer, a vocal Keystone XL opponent — made mention of the Manitoba explosion in a news release announcing a new anti-pipeline ad that will coincide with President Barack Obama's state of the union address Tuesday night.

TransCanada spokesman Shawn Howard says he believes the public will wait to find out what caused the latest incident before rushing to judgment. Howard adds that the company is aware that its response in the aftermath of the blast will be watched closely.