WASHINGTON, April 1, 2008 (AFP) - Pentagon spending on major weapons systems has rocketed to 1.6 trillion dollars, a two-decade high, with programs going over budget and falling behind schedule, a government audit found.

The Government Accountability Office (GAO) said 72 programs, ranging from fighter jets to combat ships and satellites, were over budget by 295 billion dollars in 2007 and behind schedule by an average of 21 months.

The spending on new weaponry continued to rise despite funding competition from the wars in Afghanistan and Iraq and a decline in discretionary spending in other areas of the US government budget, the GAO said.

Defense Department (DOD) investment in weapons systems doubled from 790 billion dollars in 2000 to 1.6 trillion dollars last year, the GAO said in its sixth annual report on the department's acquisitions program.

While acquisition costs were six percent higher than original estimates in 2000, they were 26 percent higher last year, the report said. Moreover, research and development costs were 40 percent over budget in 2007.

The cost overruns will be difficult to sustain as the weapons programs face stiff competition for funds from the wars as well as non-military programs such as social security, the GAO said.

The Pentagon plans to invest about 900 million dollars over the next five years on development and procurement, including more than 335 billion dollars, or 37 percent, for new major weapon systems, the report said.

'Every dollar spent inefficiently in developing and procuring weapon systems is less money available for many other internal and external budget priorities -- such as the global war on terror and growing entitlement programs (such as social security),' Gene Dodaro, the GAO's acting comptroller general, said in the report delivered to Congress on Monday.

'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,' Dodaro said.

Despite efforts to improve the acquisitions process since 2003, the changes have yet to translate into best practices on individual programs, he said.

But, he added, Pentagon leaders have launched initiatives aimed at improving the department's acquisitions process.

'Successful implementation will have significant implications for decisions made on individual programs, DOD's larger modernization goals, and the nation at large,' Dodaro said.

The Pentagon said it was too soon to respond to the report.

'Since the report came out just yesterday afternoon, we'd like to look at what GAO has said, and then at the appropriate time make an informed comment,' the Pentagon said in a statement.