A conservative watchdog group is suing the Federal Aviation Administration alleging that the agency is slow-walking the release of details relating to Transportation Secretary Peter Buttigieg’s use of government jets.

The lawsuit from Americans for Public Trust is the latest instance of conservatives criticizing Mr. Buttigieg for his use of jets as hypocrisy, citing his promotion of transportation powered by renewable energy and bike riding.

Representative Kevin Hern, who was the recipient of the 2022 Friend of Fossil Fuels Award, said that Mr. Buttigieg’s behavior was an instance of “Rules for thee, but not for me.”

“They want middle- and working-class Americans to feel bad for putting gas in their cars to get to work, but they’ll still fly private,” Mr. Hern said of the alleged flights. “The hypocrisy is infuriating for millions of Americans struggling to heat their homes as a result of Biden’s war on energy.”

The new lawsuit comes after Fox News reported that Mr. Buttigieg took at least 18 flights on government jets in the first two years of President Biden’s administration.

Combined with Mr. Buttigieg’s advocacy for a transition away from fossil fuels, conservative outlets and pundits have hammered his use of jets in the press and online.

The suit follows months of back and forth between the FAA and Americans for Public Trust, beginning in November, when the organization made its first request for information.

After two more requests for records, both in January, the FAA both set and missed deadlines to release the details of Mr. Buttigieg’s flights. Now, the nonprofit is suing the FAA.

“We’re filing suit on behalf of all Americans who deserve to know how their money is being spent by this admin,” the organization said in a statement released Thursday.

Following the report the Department of Transportation’s Inspector General opened an investigation into Mr. Buttigieg’s possible modes of transportation in February.

Mr. Buttigieg used government jets to fly to various destinations in order to promote infrastructure projects and federal grants relating to infrastructure and transportation, according to the report.

A Department of Transportation has called the investigation “cynical” and “outlandish.”

“We welcome this independent audit moving forward in order to put some of the false, outlandish, and cynical claims about the Secretary’s mode of travel to rest,” a Transportation Department representative said. “The fact remains that he flies commercially the vast majority of the time.”

Mr. Buttigieg isn’t the only executive branch official to have been criticized for allegedly improper use of government planes in recent years.

Treasury Secretary Mnuchin, who served under President Trump, was found to have flown on military aircraft 17 times in the early years of Mr. Trump’s administration, costing the taxpayers over $800,000.

“Just because something is legal doesn’t make it right,” the counsel to Treasury Inspector General Eric Thorson, Rich Delmar, said.

Mr. Buttigieg’s predecessor under Mr. Trump, Elaine Chao, faced questions of her own related to use of government planes in 2017, when it was disclosed she had flown on government planes on seven occasions costing taxpayers around $94,000.

The Secretary of Health and Human Services, Tom Price, was also found to have improperly used taxpayer-funded jets in 2017 to the tune of $1 million. The issue eventually led to Mr. Price’s resignation after he faced the prospect of being fired for his misconduct.

The Department of Transportation did not immediately respond to a request for comment.