Environmental activists Friends of the Earth Friday called on US President Barack Obama to overturn a controversial $7 billion oil pipeline project to run from Canada to the United States.

"President Obama could go a long way toward restoring trust by rejecting oil lobby influence and the Keystone XL pipeline," Erich Pica, head of the group, said in a statement.

Washington has launched consultations on the 1,700-mile (2,700-kilometer) Keystone XL pipeline which would run from the tar sands of the Canadian province of Alberta to the Gulf of Mexico in the southern US.

The final decision on whether to press ahead with the project is expected within weeks.

The Keystone XL pipeline proposed by TransCanada would begin in Alberta in western Canada and pass through the US states of Montana, South Dakota, Nebraska, Kansas and Oklahoma before ending up at refineries in Texas.

A number of environmental and citizen groups are fighting the pipeline because exploiting the unconventional oil sands of Alberta requires energy that produces a large volume of greenhouse gases.

The US State Department is handling public consultations as the pipeline would run across the border with Canada. And hundreds of people took part in a public meeting Friday, set to be one of the last before a final decision.

Earlier this week, the State Department denied claims of "complicity" with TransCanada by Friends of the Earth and insisted it had behaved "transparently and evenhandedly" toward the Keystone XL project.

In a long-awaited environmental impact statement on the project, the State Department said in August the pipeline would be safer than most current oil transportation systems.

But Friends of the Earth on Monday circulated what it sees as incriminating emails between Marja Verloop, who works at the US embassy in Ottawa, and Paul Elliott, the Washington lobbyist for pipeline operator TransCanada.

The group said the emails, part of a second batch obtained through a Freedom of Information Act request, reveal "department employees' pro-pipeline bias and complicit relationships with industry executives."

"Over the last two weeks, we've seen clear evidence that cronyism and cozy ties to oil lobbyists have corrupted the review process," Pica alleged Friday.

"It's increasingly clear that the State Department is in bed with oil lobbyists and that sustained grassroots pressure is needed to force President Obama's intervention."