WASHINGTON - US lawmakers dealt a blow to President Barack Obama's five-year-long effort to close the prison camp at the Guantanamo Bay Naval Base in Cuba by omitting a plan to shut the facility from an annual defense authorization bill.

US Senator Carl Levin, chairman of the Senate Armed Services Committee, told reporters on Monday that the final version of the massive bill will not allow the president to transfer inmates to the United States.

"Our language (on Guantanamo) ... will not be in," Levin said.

The defense bill, which has been passed annually for more than half a century, is likely to be approved by the House of Representatives and Senate in the coming days and then sent to the White House for Obama to sign into law.

Obama has promised to shut the detainee camp since he entered the White House in early 2009, citing its damage to the US reputation around the world. He has so far been unable to do so, partly because of resistance from Congress.

In its version of the National Defense Authorization Act written earlier this year, the majority-Democratic Senate panel included language that would have allowed some transfers to the United States.

Such transfers are strongly opposed by some Democrats and many Republicans, who hold a majority of seats in the House, and were left out of the compromise version of the bill.

Advocates for closing the camp say it violates US principles such as not holding prisoners without charge. They say it also acts as a recruiting tool for anti-American militants, and is very expensive to keep open.