The White House says it will make no decision on the proposed Keystone XL pipeline until after closely reviewing a newly issued report from the State Department, which found it was "unlikely" that construction of the conduit would lead to a significant increase in global greenhouse-gas emissions.

"A decision on whether the project is in the national interest will be made only after careful consideration of the (State Department environment impact study) and other pertinent information, comments from the public, and views of other agency heads," White House spokesman Matt Lehrich said.

The Obama administration said it would review the study over the coming weeks but did not indicate when it would make its decision.

The Canadian government and North American business leaders are pressuring Obama to approve the pipeline, which would be built by Calgary-based TransCanada and transport oil from the western Canadian province of Alberta to the U.S. Gulf Coast.

But environmentalists vehemently oppose the project, arguing it would trigger faster development of the Alberta oil sands.

The State Department's Final Environmental Impact Statement, however, refuted that view, saying "approval or denial of any one crude oil transport project, including the proposed project, is unlikely to significantly impact the rate of extraction in the oil sands."

It acknowledged, though, that producing oil from the Alberta tar sands results in 17 percent higher greenhouse-gas emissions than regular crude development.

The study did not specifically recommend whether or not to grant TransCanada a permit for the project, but Secretary of State John Kerry will issue a recommendation to Obama based on "national interest" after receiving input over 90 days from other federal agencies.

After the State Department's assessment was released, several Republican lawmakers urged Obama to quickly approve the project, saying it would create tens of thousands of jobs in the United States. EFE