US President Barack Obama on Friday mandated a new national policy on cutting greenhouse gas emissions and increasing fuel efficiency for pollution-spewing trucks.

Obama signed a memorandum which also expanded his effort to make cars more environmentally friendly, and stipulated new efforts to develop advanced vehicles, including electric cars, the White House said.

"I believe that it's possible in the next 20 years for vehicles to use half the fuel and produce half the pollution that they do today," Obama said.

"But that's only going to happen if we are willing to do what's necessary for the sake of our economy, our security and our environment."

The action by Obama, joined by top executives from car and truck manufacturers in the White House Rose Garden, requires US government agencies to boost fuel efficiency and reduce emissions in trucks built from 2014 onwards.

The US move was quickly mirrored by Canada, with which the United States shares the largest trading relationship in the world. Billions of dollars in freight are trucked between the two countries each year.

Obama's initiative built on a previous announcement on auto emissions by the White House for cars and light trucks which it described as equivalent to taking 177 million cars off the road.

Those standards required US automakers to boost the efficiency of cars and light trucks by 2016, four years earlier than previously required under federal law.

"One year later, we're beginning to see results," Obama said.

"Instead of fighting higher standards, auto manufacturers are engaged in a race to meet them.

"And over the next five years, we expect fuel efficiency standards in cars and light trucks to reach an average of 35.5 miles per gallon."

The president also signaled he would push for further advances in fuel efficiency standards in cars and light trucks after 2016.

"I'm proposing we start developing right now a new and higher standard to take effect beginning 2017 so that we can make more and more progress in the years to come," he said.

The announcement came as the oil slick disaster in the Gulf of Mexico underscored the dangers of over-reliance on oil as a fuel, a commodity the United States also imports in vast quantities from volatile regions of the world.

"We know that our dependence on foreign oil endangers our security and our economy," Obama said.

"We know that climate change poses a threat to our way of life," Obama said. "The disaster in the Gulf only underscores that even as we pursue domestic production to reduce our reliance on imported oil, our long-term security depends on the development of alternative sources of fuel and new transportation technologies."

The BlueGreen Alliance, a partnership of organized labor and environmentalists, praised Obama's directive, saying it would help the trucking industry become more competitive.

"We laud President Obama in setting a course for reducing truck pollution that will increase our energy independence and ensure workers have more, quality green job opportunities as we move to a clean energy future," said the group's executive director, David Foster.

But Foster voiced hope that companies -- not workers -- would pick up the tab for the transition to cleaner emission standards, saying that many truckers live near the poverty line.

Canada's Environment Minister Jim Prentice said that the government in Ottawa would join the Obama administration in "taking the next logical step," in regulating the emissions of heavy duty trucks.

The final regulations will be implemented on models between the 2014 and 2018 model year, Environment Canada said.