A senior US official said a Republican bill to deny US President Barack Obama the right to decide on the construction of an oil pipeline from Canada raises "serious" legal questions.

Kerry Ann-Jones, who is charged with reviewing the pipeline issue for the State Department, also told a legislative panel that the proposed law "overrides foreign policy and national security considerations."

Last week Obama, a Democrat, rejected the proposed Keystone XL pipeline from Canada to Texas, saying he could not vouch for its safety by a deadline despite intense election-year pressure.

Republicans had given him 60 days to make a decision on whether to approve the $7 billion, 1,700-mile (2,700-kilometer) pipeline route through the Great Plains to Texas, forcing him to choose between environmentalists and industry.

The Obama administration said TransCanada Corporation could resubmit the Keystone XL project but that officials were not able to assess its plan by a February 21 deadline put into law by the Republican majority in Congress.

According to a new bill sponsored by Republican lawmaker Lee Terry, the authority to approve such projects would fall to the Federal Energy Regulatory Commission.

The FERC "shall, not later than 30 days after receipt of an application therefor, issue a permit" for the oil pipeline, which would be implemented in line with an environmental impact statement, according to the bill.

Under existing legislation, the president has the authority to decide on the pipeline following a recommendation from the State Department, which deals with cross-border issues.

Jones told a House of Representatives subcommittee on power and energy that the bill would not resolve concerns about energy security, foreign policy, economic effects as well as the impact on health, safety and the environment.

"It just imposes narrow time constraints and creates automatic mandates that prevent an informed decision," she said, according to her prepared testimony.

"The legislation raises serious questions about existing legal authorities," said Jones, assistant secretary of state for oceans and international environmental and scientific affairs.

The bill also "questions the continuing force of much of the federal and all of the state and local environmental and land use management authority over the pipeline," she said.

And it "overrides foreign policy and national security considerations implicated by a cross border permit, which are properly assessed by the State Department," Jones said.