WASHINGTON (AFP) - President Barack Obama signed early Thursday a bill ending the two-week US government shutdown and extending the Treasury's borrowing authority.

The White House announcement was the final piece in an agonising political drama that had raised the prospect of an unprecedented US debt default and rattled markets around the world.

Office of Management and Budget Director Sylvia Mathews Burwell said in a separate statement that the government will try to get back to full operating status as smoothly as possible.

"This has been a particularly challenging time for Federal employees and I want to thank our Nation's dedicated civil servants for their continued commitment to serving the American people," she wrote.

Most employees furloughed for the past two weeks are expected back to work on Thursday, Ms Burwell said in a directive to federal agencies.