Defence Minister Richard Marles has been compared to high-flying former Liberal Bronwyn Bishop as he faced a grilling over his office’s $3.6 million flight bill.

Mr Marles defended the taxpayer-funded bill, but cited security reasons for his refusal to reveal more details about the flights on Friday.

“A lot of people travel on those flights, my direct component is a fraction of the number that has been reported,” Mr Marles told Today Show co-host Karl Stefanovic.

“Everywhere I have gone, everything I have done has been on behalf of the Australian people and the duties I do in that regard, and I stand by every flight I have taken.

“My preference would be to have all of that out there because that would make things much clearer, but there is a genuine security issue here.”

Mr Marles’ office has authorised hundreds of hours of special RAAF flights since April last year. The flights have been used by him and guests such as senior defence personnel and other MPs.

The spending was unearthed in documents obtained by Greens senator David Shoebridge. They show that only Prime Minister Anthony Albanese has spent more on VIP travel in the same period.

The documents, released under freedom of information laws, also show that Mr Marles was involved in a decision earlier this year to ban the release of information revealing where government VIP planes flew and who was on board.

That move followed advice from security agencies that special purpose flight destinations could make travellers vulnerable. The government decided instead to publish expenditure reports without flight details.

News.com.au alleged this week that the Victorian MP’s flights included booking military planes to pick him up and drop him off at Avalon airport, closer to his home in Geelong – saving a one-hour chauffeur-driven car ride.

Mr Marles’ office has said previously that his travel complies with relevant guidelines and security procedures, and that he routinely travels on commercial flights.

The office also said his spending was comparable with that of previous defence ministers, including Peter Dutton and Barnaby Joyce.

But the revelations prompted Mr Dutton to make an unflattering comparison with Ms Bishop, who infamously charged taxpayers $5000 in 2015 for a short helicopter flight to a Liberal Party function.

“The difficulty Richard has got, if you go through social media, he ripped into Bronwyn Bishop at the time for spending $5000 I think it was for a helicopter,” Mr Dutton told Today on Friday.

“There is a double standard that is operating here … he puts Bronny to shame.”

The Greens are expected to try to team up with the Coalition when parliament resumes next week, to dig further into Mr Marles’ travel bill.

“When Labor was in opposition, it quite rightly demanded transparency in the use of these extremely expensive VIP flights,” Senator Shoebridge told the Nine papers.

“Now they are in government and very actively using these flights, Labor’s love of transparency has turned decidedly cold.”