WASHINGTON (Reuters) – Several Democratic members of the U.S. Senate and House of Representatives asked on Wednesday for an investigation into a report that Health and Human Services Secretary Tom Price used private jets to travel on government business.

Politico reported on Tuesday that Price took private jets on five occasions for official business, which cost tens of thousands of dollars more than commercial flights. Politico documented one chartered trip to Philadelphia from Washington that cost about $25,000.

“American taxpayers deserve assurances that their tax dollars are not wasted by the government’s highest officials,” five lawmakers said in a letter to the HHS Office of the Inspector General, citing the Politico report.

They asked for a review of Price’s “adherence to federal regulations and Department of Health and Human Services policies and procedures for travel.”

The lawmakers included Frank Pallone Jr., the top-ranking Democrat on the House Energy and Commerce Committee, and Senator Patty Murray, the top-ranking Democrat on the Senate Health, Education, Labor, and Pensions Committee.

HHS said in a statement that the agency’s travel department “continues to check every possible source for travel needs including commercial, but commercial travel is not always feasible.”

Last month, U.S. Treasury Secretary Steve Mnuchin and his wife, actress Louise Linton, traveled on a government plane to Kentucky where they viewed the Aug. 21 solar eclipse with Senate Republican leader Mitch McConnell and others. That trip prompted a federal watchdog this month to review the circumstances surrounding the travel.