WASHINGTON -- The chairman of the Senate Veterans Affairs Committee on Wednesday called for more centralized control of the VA medical system after recent breakdowns in cleaning colonoscopy equipment exposed thousands of veterans to the risk of contracting HIV and other infections.

Disparities in quality control procedures at VA medical centers raise questions about whether local, regional or national leaders are in charge, Democratic Sen. Daniel Akaka of Hawaii said in a statement before the committee hearing.

"True quality assurance has to be managed across the system and that means central office must exercise greater control," Akaka said, adding that he expects the question to be a major issue at upcoming confirmation hearings for top VA staff.

VA spokeswoman Katie Roberts said the agency was releasing $26 million from reserve funds to buy new equipment to improve the cleaning of endoscopes and other reusable medical devices. The announcement came as VA officials continued taking heavy criticism on Capitol Hill over botched colonoscopies and other endoscopic procedures in Miami, Augusta, Ga., Murfreesboro, Tenn., and Mountain Home, Tenn.

Sen. Richard Burr, the top Republican on the committee, said the VA's problems have persisted despite repeated safety alerts and warnings since at least 2003.

"The more I learn about this case, the more it seems to be a case of extreme negligence," Burr said. "With multiple past incidents, multiple warning signs ... there is no possible justification as to why this still has not been corrected."

He and other lawmakers questioned whether the agency's national center overseeing patient safety, based in Ann Arbor, Mich., is high enough on the organizational chart.

Experts have recommended that VA adopt more standardized procedures for cleaning the equipment.

Thomas Nolan, a senior fellow with the Institute for Healthcare Improvement, told lawmakers that human errors would likely continue without a better system, even with extra training and prodding from management. He noted how fewer customers left their bank cards in ATMs after banks changed the machines so that the cards were released before money was dispensed.

The VA began warning about 10,000 former patients in February that they may have been exposed to infections as far back as 2003. Although the VA says the chance of infection was remote, the patients were advised to get blood tests for HIV and hepatitis.

The agency says six veterans subsequently tested positive for HIV, 34 tested positive for hepatitis C and 13 tested positive for hepatitis B. But there is no way to prove whether the infections came from VA procedures, and some experts say most or all of the infections probably already existed.

The VA says the rate of infections is consistent with or less than what would normally be found among similar populations. But the agency is investigating the cases for connections.

The VA has said the errors were limited to the three states, but a report released last week by the agency's inspector general suggested more widespread problems.

Even after the well-publicized scare, investigators conducting surprise inspections in May found that only 43 percent of the agency's medical centers had standard operating procedures in place for endoscopic equipment and could show they properly trained their staffs for using the devices.