Rep. John Mica (R-Fla.) has released a report saying the federal government could reduce spending by $500 million a year if it cut back on wasteful government conferences.

The report from Mica, who chairs the House Oversight & Government Reform subcommittee on Government Operations, said congressional oversight of the IRS, General Services Administration (GSA) and two other agencies has already helped save $219 million over the last few years. It says more savings are possible if Congress casts a wider oversight net.

"Based on estimated savings from these four agencies over past years, government wide savings from reductions in conference spending could reach as high as half-a-billion dollars annually," the report said.

The report credits congressional oversight with forcing federal agencies to make significant cuts to conference budgets. The notorious 2010 GSA conference in Las Vegas cost more than $800,000, and sparked oversight of conference spending at several federal agencies.

"At that time, Department and Agency conference planners contracted with little regard for budgetary considerations," Mica's report said. "As a result, taxpayers were forced to pay for outrageous federal junkets.

"Some of these conferences included high-priced food and entertainment as well as promotional items and improperly accepted gifts. Unfortunately, wasteful spending on federal conferences is not unique to a specific agency."

Mica's report said that since congressional scrutiny of GSA, that agency's conference budget has fallen nearly 90 percent, from $10.9 million in 2010 to just $1.3 million in 2012.

The report says a similar cut happened at the IRS in the wake of oversight of that agency's conferences. The IRS conference budget fell from $37.6 million in 2010 to $4.9 million in 2012, an 87 percent cut.

Congress has also investigated wasteful conferences at the Department of Veterans Affairs (VA) and the Defense Department. Conference spending at the VA fell from $86.5 million in 2011 to $7.5 million in the first three quarters of 2012.

Defense saw a similar decline, from $89 million in 2012 to $12.3 million in the first six months of 2013.