Updated

A Canadian company that hopes to pipe oil from western Canada to Texas is working with U.S. officials to develop safety standards beyond those required by law, Secretary of State Hillary Rodham Clinton said Thursday.

The new standards should ensure that if a permit for the 1,900-mile pipeline is issued, "the project will be as safe as it could possibly be," Clinton said.

"We've been clear from the beginning that the safety of the pipeline is one of our highest priorities," said Clinton, who is expected to decide on the project by the end of the year.

The State Department has authority over the pipeline because it crosses an international boundary.

Calgary-based TransCanada wants to build a pipeline to carry crude oil extracted from tar sands in Alberta, Canada, to refineries in Houston and Port Arthur, Texas.

James Millar, a spokesman for TransCanada, said the company has agreed to 57 conditions above and beyond industry standards for the $7 billion Keystone XL project. Among other changes, the company has agreed to build the pipeline 4 feet below ground, instead of 3 feet, and will allow an increased number of inspections, Millar said. It also will install a greater number of safety shut-off valves than usual.

Besides the State Department, at least two federal agencies — the Environmental Protection Agency and the Pipeline and Hazardous Materials Safety Administration — are reviewing the project.

The State Department is expected to complete an environmental analysis this month, and officials have scheduled a series of public meetings this fall in states where the pipeline will travel, including Montana, South Dakota, Nebraska, Kansas and Oklahoma.

Appearing at a news conference with Canadian Foreign Minister John Baird, Clinton said officials were "leaving no stone unturned in this process," including a review of hundreds of thousands of comments from the public.

"We have worked diligently to make sure that we have full understanding of all of the consequences, including the very important point that the minister made to me about energy security and what that means for our two countries," Clinton said.

Baird called Keystone XL "a very important project, not just for our government but for Canadians and the future of the Canadian economy." He said he was pleased that U.S. officials have scheduled public meetings this fall and looks forward to the U.S decision.

The project would double the capacity of an existing pipeline from Canada, and supporters say it could significantly reduce U.S. dependence on Middle Eastern oil.

Environmental groups say the pipeline would bring "dirty oil" that requires huge amounts of energy to extract and could cause an ecological disaster in case of a spill.

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Associated Press writer Matthew Lee contributed to this report.

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Online:

State Department Keystone XL website: www.keystonepipeline-xl.state.gov/clientsite/keystonexl.nsf?Open

Follow Matthew Daly on Twitter at http://twitter.com/MatthewDalyWDC