 -- Department of the Interior Secretary Ryan Zinke is the latest member of President Donald Trump’s cabinet to come under scrutiny for flying chartered and military aircraft at taxpayers’ expense.

According to Interior Department spokeswoman Heather Swift, Zinke has chartered three flights since March, including a June 26 flight from Las Vegas to Kalispell, Montana, which incurred a cost of $12,375.

Another chartered flight shuttled Zinke between the Caribbean islands of St. Croix and St. Thomas for the U.S. Virgin Islands Centennial Transfer Day Ceremony.

Politico was first to report on the chartered flights.

In a statement, Swift said “the Secretary traveled on charter flights when there were no commercial options available,” adding that the department’s ethics office approves all travel in advance of booking.

Zinke also shared a military aircraft with U.S. Department of Agriculture Secretary Sonny Perdue to attend a briefing at a wildfire camp in Montana, Swift said. Tim Murtaugh, a spokesman for the USDA, said Zinke and Perdue were traveling to meet firefighters and assess the situation at the Lolo Peak fire in August.

"Though Secretary Perdue usually travels on commercial flights, in this instance there were no viable commercial options available to transport two Cabinet secretaries, security details, and associated staff from USDA, the Forest Service, and the Department of the Interior to Missoula, Montana in the time required," a spokesperson for the USDA said in a statement to ABC News.

On Friday, Zinke responded to the report, calling it "a little B.S. on travel" during a speech to the Heritage Foundation in Washington, D.C.

The secretary detailed the occasions when he flew charter and military planes, explaining that it happens out of necessity when he travels "in areas and under circumstances that [he doesn't] have other flight options."

"I intend to continue flying in the benefit of official duties," said Zinke, adding, "Every time I travel I submit the travel plan to the ethics department that evaluates it line by line to make sure that I am above the law and I follow the law."

This week, as reports of Health and Human Services Secretary Tom Price’s proclivity for chartering pricey private flights made headlines, Trump expressed growing frustration and said he’s “not happy about it” on Wednesday.

On Thursday, Price vowed to reimburse taxpayers for the cost of his seat on chartered flights to the tune of $51,887.31.

Treasury Secretary Steve Mnuchin and Environmental Protection Agency Administrator Scott Pruitt have also been cited as frequent flyers of private planes. On Wednesday, the House Oversight Committee opened an inquiry into federal agency travel.

Press secretary Sarah Sanders was asked about the controversy in her press briefing on Thursday, and reiterated the flights for HHS personnel would be halted.

"The White House does not have a role on the front end of approving private charter flights at the agencies and that's something that we are certainly looking into from this point forward and have asked a halt to be put particularly at HHS on any private charter flights moving forward until those reviews are completed," Sanders said.

ABC News' Katherine Faulders and Adam Kelsey contributed to this report.