WASHINGTON — The head of the Environmental Protection Agency used public money to have his office swept for hidden listening devices and bought sophisticated biometric locks for additional security.

The spending items, totaling nearly $9,000, are among a string of increased counter-surveillance precautions taken by EPA Administrator Scott Pruitt, who also requires around-the-clock protection by an armed security team. The EPA's Office of Inspector General is already investigating Pruitt's $25,000 purchase of a custom-made soundproof privacy booth for his office to deter eavesdropping on his phone calls.

An accounting of Pruitt's spending for the bug sweep and pricey locks was provided to The Associated Press by an EPA employee who spoke on condition of anonymity, citing concerns of retaliation.

EPA spokesman Jahan Wilcox defended the spending.

"Administrator Pruitt has received an unprecedented amount of threats against him and while The Associated Press attempts to trivialize his safety, there is nothing nefarious about security decisions made by EPA's Protective Service Detail," Wilcox said Monday.

EPA's headquarters in Washington is a secure building, with armed guards posted at the entrances and metal detectors and X-ray machines for scanning visitors and their bags.

EPA paid $3,000 in April to Edwin Steinmetz Associates to conduct the bug sweep. The purchase of the biometric locks, which typically work by electronically scanning a person's fingerprint, was spread over two transactions earlier this year of $3,390 and $2,495.

Expenses under $3,500 are not typically listed on a federal contracting website that provides public disclosure of government spending.

EPA employees don't typically deal with government secrets, though the agency does occasionally receive, handle and store classified material because of its homeland security, emergency response and continuity missions.

In an interview last week, security contractor Ed Steinmetz declined to comment on his work for specific clients, citing non-disclosure agreements. He confirmed, however, that $3,000 is his standard rate for a one-day job.

Steinmetz said he specializes in using sophisticated detectors to scan for tiny listening devices hidden in furniture or walls, as well as in other electronic devices such as computer mice or phone chargers. He can also runs checks to see if a phone line is tapped.

"I can't confirm or deny EPA," said Steinmetz, a former police officer who said he has worked as a contractor for about 15 federal agencies. "However, that would be an agency that if you have confidential information being discussed that could negatively impact their operation, they would want to know about it."

Wilcox said that under the Obama administration, then-EPA Administrator Lisa Jackson also had her office swept for listening devices. Wilcox declined to provide the specific details of that spending, including the year and amount.

Asked about the special phone booth in his office during a congressional oversight hearing earlier this month, Pruitt said the purchase was justified because he needs a secure phone line in his office to communicate with officials at the White House, located just a few blocks away.

None of Pruitt's predecessors installed a similar phone setup.