An Interior Department watchdog found that Secretary Ryan Zinke violated federal policy when he let his family members travel with him in government vehicles, although he had reimbursed the department.

A copy of the department’s inspector general report was sent to Congress and was provided to Roll Call by a congressional aide on Thursday.

The inspector general’s office reached its findings after investigating allegations that Zinke had made numerous trips, including in private and military jets, at taxpayer expense.

Rep. Raúl M. Grijalva of Arizona, the top Democrat on the House Natural Resources Committee, which oversees the department, complained that “Republicans have known about Secretary Zinke’s scandals for 18 months and done nothing.”

Zinke had also asked Interior Department employees about whether his wife could join the department as a volunteer, according to the IG.

“He denied that his intention in making this request was so that his wife could travel with him in an official capacity, which would have eliminated the requirement to reimburse the Government for her travel,” the report said. “Ultimately, the employees advised him that making her a volunteer could be perceived negatively, and she did not become one.”

Zinke also cost taxpayers $25,000 when he took an unarmed security detail with him during a vacation to Turkey and Greece, the IG said in its report.

The report comes as the Interior Department is dealing with public backlash over news reports that Zinke had attempted to hire Suzanne Tufts, a political appointee at the Department of Housing and Urban Development, to serve as Interior’s acting inspector general. The Interior Department has since denied any such move and blamed it on an incorrect email sent by HUD Secretary Ben Carson, according to The Washington Post, which reported on the IG report earlier Thursday.

The IG’s investigation also found that Zinke in March 2017 directed his security detail to drive someone who was not a government employee to the airport after a dinner, against agency rules.

“Secretary Zinke acknowledged that he told his detail to take the non-Government employee to Reagan National Airport,” the report said. “He said he had asked this as a matter of convenience, but he was later told not to make such requests and he has not done so since.”

The agency cleared Zinke of allegations that a department employee had resigned over requests that she walk his dog. The employee told the investigators she walked Zinke’s dog voluntarily and had instead resigned because she did not receive a position she wanted.

“The Inspector General report proves what we have known all along: the secretary follows all relevant laws and regulations and that all of his travel was reviewed and approved by career ethics officials and solicitors prior to travel,” Interior spokeswoman Heather Swift said in an email. “Concerning the internal travel policy, that has been updated to reflect the reality of the long standing situation.”

Democrats and environmental groups have for months been frustrated over the refusal by the Republican majority to hold oversight hearings to examine the spending and travel habits of Trump administration officials, including Zinke and former EPA Administrator Scott Pruitt, who resigned amid a long list of spending and management scandals.

The latest report on Zinke is likely to cause them to amplify calls for oversight and for his resignation, although the White House has not given any indication that it would fire Zinke.

“Being exposed for abusing his power to rip-off the taxpayer while benefiting himself provides all the proof that should be needed to fire Ryan Zinke,” Sierra Club Executive Director Michael Brune said in a news release. “It’s time Donald Trump fires Ryan Zinke, not give him a chance to engage in a Washington cover-up.”