WASHINGTON - The State Department said Friday that a new environmental study of an oil pipeline from Canada to Texas shows no new issues since a similar report was issued last year.

The report on the proposed $7 billion, 1,900-mile (3,057-kilometre) pipeline, comes as President Barack Obama offered his first public comments on the project, which would carry crude oil extracted from tar sands in western Canada, to refineries in Texas. At a town hall meeting on energy last week, Obama said concerns about the potentially "destructive" nature of the Canadian oil sands need to be answered before his administration decides whether to approve a permit for the Keystone XL pipeline.

The pipeline planned by Calgary-based TransCanada would travel through six U.S. states carrying what environmental groups call "dirty oil," because of the intensive energy needed to extract crude from formations of sand, clay and water.

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

Obama used the phrase "tar sands" -- the term favoured by environmentalists -- to describe the bitumen deposits embedded in Alberta, Canada sands, but refused to offer an opinion about whether the pipeline should be approved.

"These tar sands, there are some environmental questions about how destructive they are, potentially, what are the dangers there, and we've got to examine all those questions," Obama said at an April 6 town-hall meeting in Pennsylvania.

Obama said he could not comment on the specifics of the Keystone XL pipeline, because the State Department is going through a complicated review process, "and if it looks like I'm putting my fingers on the scale before the science is done, then people may question the merits of the decision later on."

Still, Obama noted that Canada is one of the largest oil exporters to the United States. "I will make this general point, which is that, first of all, importing oil from countries that are stable and friendly is a good thing," he said.

Environmental groups were heartened by Obama's comments, but disappointed by the State Department review.

Susan Casey-Lefkowitz, international program director for Natural Resources Defence Council, said the 320-page report glossed over crucial issues such as pipeline safety and the risks posed by the proposed route over the massive Ogallala Aquifer, which supplies drinking water to people in eight states.

"If this round of the Keystone XL tar sands pipeline environmental review is as superficial as it seems, the State Department will need to go back to the drawing board -- perhaps the third time will be a charm and they will get it right," she said.

The pipeline project has been delayed since last summer, when the U.S. Environmental Protection Agency asked the State Department to conduct a supplemental environmental impact study to address concerns about pipeline safety and the impact on climate change of oil sands production.

In its new report, the State Department appeared to argue against a route change for the 36-inch pipeline.

Experience "from previous oil line releases in shallow groundwater areas ... indicates that the impacts from even large spills would likely be limited to localized groundwater contamination that would not threaten the regional viability of the aquifer system," the report says.

The State Department says it will decide whether to grant a permit for the project by the end of the year. The department has authority over the pipeline because it crosses an international boundary.