A watchdog group asked the Interior Department's inspector general on Friday to investigate whether Secretary Ryan Zinke violated the law by chartering private planes for purposes that may represent conflicts of interest.

The Campaign for Accountability, a watchdog group focused on public accountability, asked both the Interior Department's Office of Special Counsel and the inspector general to investigate whether Zinke violated conflict of interest laws and the Hatch Act by using private charter flights to travel for public speaking events, including addressing professional sports teams, as part of his official duties.

"Interior argues that by speaking to a group of highly paid – mostly foreign – athletes, Sec. Zinke was reaching ‘a key audience of people we are trying to target to use our public lands,'" said Daniel Stevens, the group's executive director.

"Shouldn't Sec. Zinke be more focused on American families and how they can benefit from our national lands? Rather than putting America first, Zinke is putting a top donor first," said Stevens.

An agency inspector general office tends to take requests for investigations seriously, and will tell the group whether or not it will procede with an investigation within a specified timeframe.

Politico first reported on Thursday that Zinke chartered private and miltary transport planes at a cost of $12,000. The news broke after Environmental Protection Agency chief Scott Pruitt was found to have spent $58,000 on private flights. But that is next to nothing when compared to Health and Human Services Secretary Tom Price who spent about $1 million in military and private flights. Price resigned on Friday over the allegations.

Cabinet secretaries are required to use commercial airlines for travel, with restrictions on the use of private charter flights and military transportation. Zinke on Friday called the dust up over the flights "a little B.S.," but that was before Price resigned.

The watchdog group pointed out that the Washington Post reported on Thursday that Zinke had taken a private charter plane in June following a "motivational speech" to the Vegas Golden Knights, a National Hockey League team based in Las Vegas, Nev.

The team is owned by Bill Foley, the chairman of Fidelity National Financial, which had been a campaign contributor to Zinke's two congressional races when he served in the House.

"In addition, Fidelity National Financial and affiliates donated $1 million to President Trump's inaugural committee," according to the group.

The group argues that Zinke's trip to Las Vegas to speak to the team, "whose owner has been a major benefactor to both Mr. Zinke and President Trump, seems to be a special favor provided to a major political supporter, in violation of conflict of interest laws."

It added that Zinke's motivational speech may also be considered a "prohibited political activity under the Hatch Act, which bars executive branch employees from engaging in political activity while on duty."