The Australian government is fighting to hide Tony Abbott’s letters to the Queen about his much-ridiculed bid to bring back knight and dame honours, despite the information watchdog ordering the documents be produced.

The freedom of information expert William Summers has spent years attempting to secure the release of correspondence between Australian prime ministers and the Queen. The correspondence, penned between 2013 and 2016, includes 14 letters from Malcolm Turnbull and Abbott. At least one letter relates to Abbott’s infamous decision to bring back knight and dame honours in Australia.

Abbott reintroduced knighthoods in March 2014, a decision that surprised even his own cabinet, who were not consulted. He handed a knighthood to Prince Philip on Australia Day 2015, causing widespread outrage and ridicule, including among his own colleagues.

Even Rupert Murdoch, an avid supporter of Abbott, slammed the decision as a “joke and embarrassment”.

The Department of Prime Minister and Cabinet initially refused to release the letters, arguing they would damage the international relations of the Commonwealth and undermine trust in Australia’s ability to handle confidential communications. It also argued they were exempt from release as “deliberative documents”.

But Summers took his case to the information commissioner, arguing the Queen was Australia’s head of state and received the letters in that capacity, meaning there could be no risk to international relations.

The information commissioner agreed and ordered the government to make the documents transparent.

“I am not persuaded that the public interest factors against disclosure raised by the department outweigh the public interest factors in favour of disclosure,” the information commissioner ruled.

But the department is still refusing to hand over the letters, instead launching proceedings in the administrative appeals tribunal to keep them secret.

“On the day PM&C were supposed to hand over the letters, I was notified that the department had instead made an appeal to the administrative appeals tribunal (AAT) to try to block release of the letters,” Summers said.

That appeal is being heard in Canberra on Thursday and Friday.

The proceedings have been protracted and costly for Summers. He made the request roughly two and a half years ago and is now having to cover costs out of his own pocket.

Summers is aided by pro-bono representation from two barristers, Jason Pizer, QC, and Graeme Hill, and has started a crowdfunding effort to cover his and his team’s costs.

“I’m not going to roll over on this,” Summers wrote on the crowdfunding site. “I have already put a lot of time and effort into making my case (and winning it). I am going to fight the government’s legal action and make sure these letters are released.

“I have never been through an appeal like this before. In honesty, I don’t know how long it is going to take or how much it is going to cost.”

The department said it was inappropriate to comment, given the ongoing legal proceedings. It said in a statement that it received the request in November 2016, and made its decision in January 2017. The information commissioner took about a year to make a decision, the department said.