The new US envoy to Canada will tour Alberta's oil sands tomorrow to help President Barack Obama's administration formulate policy on a major source of energy supply, but one tagged as having a large environmental impact.

David Jacobson, named as ambassador to Canada last month, said today that officials in both countries recognised there must be a balance between the need for energy security and protecting the air, land and water.

"I've learned a lot about the tremendous strides that have been taken over the last several years with respect to improving the environmental record in treating the oil sands," Jacobson told reporters at a ceremony to welcome him to Calgary.

"I understand a good bit of work is still under way and I'm looking forward to going there tomorrow to learn more about it," he said in a Reuters report.

Canada is the largest foreign supplier of oil and gas to the United States, and its oil sands in northern Alberta represent the biggest deposits of crude outside the Middle East.

But in the lead-up to international climate talks in Copenhagen in December, environmental groups such as Greenpeace have intensified campaigns to highlight the impact of oil sands developments on the fight against global warming.

The Canadian oil industry has also expressed worry that energy legislation being developed in Washington could mean new restrictions on oil sands shipments due to the developments' high carbon emissions.

Jacobson said the US healthcare debate has eclipsed work on energy legislation in Congress, meaning the odds of major energy policy decisions being made in the near future are slim.

Senate Democrats recently unveiled their version of a climate change bill that was narrowly passed by the US House of Representatives earlier this year.

With a packed legislative agenda, however, it's unclear whether Congress will be able to vote on the bill before next year.

"What I think the energy bill is ultimately going to look like is a work in progress," he said.

"But one of the things that I want to do here is ... to learn as much as I can so that I can pass the word back to my colleagues in Washington so that any decisions that they do make are as informed as they can possibly be."