EPA chief Scott Pruitt cost taxpayers more than $163,000 by taking first-class flights, military aircraft and charter flights in his first year in office alone, a new report says.

Pruitt's penchant for taking first-class flights for official travel, instead of flying coach per his own agency's guidelines, by itself cost more than $105,000, according to Politico, which cites Environmental Protection Agency records.

The first-class tally — which includes $16,217 in airfare for a Morocco trip — was not previously public. It came to light because of EPA records turned over to the House Oversight Committee.

The $58,000 in costs from Pruitt's use of charter flights and a military plane was already known. For example, Pruitt and staffers flew by Air Force jet to Cincinnati from Washington for an event with President Donald Trump. That flight alone cost more than $36,000.

Another new report, from the private watchdog group Environmental Integrity Project, revealed that a trip Pruitt and staff took to Italy last year on a combination of commerical flights and a military plane cost taxpayers more than $120,000. That includes more than $30,000 in costs related to his security detail alone.

Pruitt's travel practices are the subject of an ongoing probe by the EPA's Office of Inspector General.

Pruitt had been flying first class instead of coach at the recommendation of his security team, according to the EPA.

In an emailed statement to CNBC on Wednesday, Pruitt's spokesman Jahan Wilcox said that a letter sent to the Oversight Committee explains that "EPA's Protective Service Detail identified specific ongoing threats associated with Administrator Pruitt's travel and shifted his class based on certain security protocols that require him to be near the front of the plane."

Three weeks ago, Pruitt told CBS News he would start flying coach.

Pruitt is just one of several top officials in the administration of President Donald Trump to come under fire for using pricey travel options instead of flying coach.

Trump's first Health and Human Services secretary, Tom Price, resigned last year after news stories exposed that he racked up close to $1 million in costs to taxpayers from chartering private planes and flying on military aircraft.

Last week, a private watchdog group released a report detailing how Treasury Secretary Steven Mnuchin's frequent use of military planes had cost nearly $1 million in less than one year. An internal Treasury investigation found no wrongdoing by Mnuchin.

At the Interior Department, Secretary Ryan Zinke is facing an investigation by the agency's inspector general related to reports that he had flown on a private plane that is owned by oil executives. The IG's office reportedly has received multiple complaints about Zinke's use of chartered flights.

In February, Veterans Affairs Secretary David Shulkin was hit with a scathing report by the VA's own inspector general, who found that Shulkin's chief of staff had altered a document so that the department would pay for Shulkin's wife to travel to Europe with him at a cost to taxpayers of $4,312.

The same report said Shulkin improperly accepted tickets during that trip to the Wimbledon tennis tournament in England.