WASHINGTON, April 1 (Xinhua) -- The U.S. Defense Department's spending on weapon systems has surged to 1.6 trillion dollars in 2007, doubling from 790 billion dollars in 2000, said a congressional report released on Tuesday.

    According to the report by the Government Accountability Office(GAO), the acquisition costs were 26 percent higher than the original estimates in 2007, and the spending on research and development were 40 percent over the budget.

    Despite the higher-than-budget cost, about 72 programs were still falling behind schedule by averagely 21 months, including fighter jets, combat ships and satellites, the sixth annual report on the Pentagon's weapon programs.

    However, the Defense Department, whose personnel and budgets have been strained by the Iraq war and Afghanistan war, still plans to invest about 900 million dollars over the next five years in weapon systems' development and procurement, it added.

    Gene Dodaro, the GAO's acting comptroller general, accused the defense budgets "spent inefficiently in developing and procuring weapon systems" of compromising "many other internal and external budget priorities."

    "These inefficiencies also often result in the delivery of less capability than initially planned, either in the form of fewer quantities or delayed delivery to the warfighter," he said.

    In response, the Pentagon said in a statement that the department would make an informed comment after reading the report.