There is no credible evidence to support allegations that Canada's oil sands are the most "environmentally destructive project on Earth," says a report from the Royal Society of Canada.

Yet the 438-page report, released Wednesday, identifies "serious deficiencies" in the environmental impact assessment process and points out that water monitoring of oil sands projects is set at a lower standard than for forestry.

Still, the report urged all levels of government to research independently the health impacts of oil sands projects.

Even though oil sands are a relatively small contributor to Canada's greenhouse gas emissions, the report states, they "pose a major and growing hazard" to Canada's ability to meet international commitments to reduce greenhouse gases.

The International Energy Agency says Canada ranks second only to Saudi Arabia in terms of proven oil reserves, most of which come from northern Alberta's oil sands deposits, which contain an estimated 170 billion barrels of recoverable oil.

The RSC report warned that provincial and federal environmental regulations aren't keeping pace with the rapid expansion of the oil sands, with a confusing process prone to "political interference." Ottawa, the authors say, needs "to show some leadership."

The authors urged the federal and provincial governments "to look ahead to a time when an economy based on fossil fuels may no longer be viable."

The report said that Alberta's current policy on liability for land reclamation has significant loopholes whereby taxpayers could be left with the cost of cleaning up oil sands if developers don't meet commitments.

Attempts by the federal and provincial governments to address deficiencies highlighted in the report "have been ineffective, with a much greater emphasis on expanding oil sands development rather than on ensuring the environment and Canadians are protected," said Jennifer Grant, oil sands director of Alberta environmental research group the Pembina Institute, about the RSC report.

Production from oil sands more than doubled, from 600,000 barrels per day in 2000 to 1.35 million bpd in 2009 says a recent report from IHS Cambridge Energy Research Associates. It projects that the oil sands have even more potential -- ranging from 3.1 million to 5.7 million barrels per day by 2030.

The reserves have attracted tens of billions of dollars in recent investment from some of the world's energy giants.

Canadian oil sands are likely to become the largest single source of imported oil to the United States this year and could ultimately supply more than a third of America's foreign oil by 2030 the HIS report predicted.