Senior department officials haven't provided proper oversight to ensure the billions of dollars' worth of purchases functioned as they should and were within budget, the congressional Government Accountability Office said in the report issued Thursday.

The GAO said Homeland Security's main problem was the lack of follow-up on its own procedures that were established to make sure taxpayer dollars were "being spent wisely, efficiently and effectively," USA Today reported.

Previous audits documented problems with individual programs but the latest GAO report is the first to examine Homeland Security's overall system of buying and maintaining $60 billion of equipment and technology. The report found that 45 of 48 major acquisitions didn't receive regular oversight by a board created for such reviews and that 14 of those projects experienced cost overruns and delays.

The GAO blamed the problems on insufficient Homeland Security staff and limited attention paid by senior officials.

In a statement accompanying the GAO report, Homeland Security noted improvements have been and will continue to be made.