Federal regulators in North America are under pressure from industry bodies and environmental advocates worried about the safe transport of oil by rail.

North American crude oil production has increased to the point that there's not enough pipeline infrastructure to handle deliveries. That leaves energy companies to rely more on rail as an alternate transit method and, with that, comes more derailments involving trains carrying oil.

Canadian officials are still responding to a March 7 derailment of a Canadian National Railway Co. train carrying crude oil through Ontario. Three of the 39 cars that derailed fell into an area river in a ball of flames.

Canadian Transport Minister Lisa Raitt announced new regulations in April aimed at increasing safety on the Canadian rail system. The measure from regulator Transport Canada started with an order to remove around 5,000 tanker cars designated DOT-111 from service almost immediately.

The Transportation Safety Board of Canada said the March 7 derailment involved class 111 tank cars carrying crude oil. Kathy Fox, chair of the safety board, said she's concerned about the lack of adequate safety standards, adding it was time to replace or retrofit existing tanks cars.

"Canadians expect their government to ensure that the risks posed by the transportation of flammable liquids are minimized to the greatest extent possible," she said in a statement Tuesday.

The Ontario derailment was the second such incident in the same month for CN and came about two weeks after a crash involving a CSX train carrying crude oil through West Virginia. The CSX derailment involved newer CPC-1232 model rail cars.

A February briefing from the U.S. Pipeline and Hazardous Materials Safety Administration found CPC-1232 were "marginally" better than older cars.

Advocacy group ForestEthics said it was concerned that lobbying groups in the United States were influencing federal decision-making processes on rail safety. Six of the lobbyists it found through a Freedom of Information Act request were former members of Congress.

Campaign director Ross Hammond said the U.S. government needs to be more transparent about its discussions.

"Though it might be hard for safety officials to hear over the din of all these lobbyists, the facts on these trains speak loud and clear," he said in a statement.