Former foreign affairs minister Alexander Downer has confirmed he was offered a success fee to help free one of two Australians jailed in Dubai but, in the end, he did not send a bill because he did not think it would be ethical.

Mr Downer, who is about to become Australia’s High Commissioner to London, was working as a lobbyist in 2009 when a lawyer for Matt Joyce, one of the two property executives held on suspicion of a bribery plot, asked for his help and offered a reported $60,000 success fee.

Mr Downer’s letter to the Crown Prince of the United Arab Emirates suggested bail for Mr Joyce but it made no mention of his jailed colleague, Marcus Lee.

Mr Lee’s wife, Julie Lee, has told the ABC’s Foreign Correspondent that they could not afford to pay for such help. Mr Downer told the program: "I just simply wasn’t approached about him, so I simply do not know about his case."

In an interview with Fairfax Media, Mr Downer denied that the revelation of a mere discussion about a success fee was embarrassing in the light of his new diplomatic posting.

‘‘It’s not embarrassing because I didn’t take any money and I didn’t think it was right to,’’ he said.

Asked if the $60,000 offer was correct, he said he could not recall.

‘‘I have no idea,’’ Mr Downer said. ‘‘It’s irrelevant. I didn’t accept it. I didn’t send an invoice ... The premise of your question is whether you think earning money is embarrassing, which would demonstrate you don’t know anything about business, but secondly, to be a bit fairer, since I didn’t take any money that dismisses the whole issue.’’

Mr Downer, who had been Australia’s longest-serving foreign minister in the Howard government until 2007, was working with former Labor minister Nick Bolkus in their lobby firm Bespoke Approach at the time of the request from Mr Joyce’s representative.

He would not confirm the nature of the intervention he made, but Fairfax Media has obtained a copy of the letter he sent to the Crown Prince of the United Arab Emirates, General Sheikh Mohammad bin Zayed Al Nahyan, in late April 2009. By then, both Mr Joyce and Mr Lee had long been named in media reports about two Australians jailed in Dubai.

Mr Downer told the Crown Prince that the case had become controversial in Australia and it ‘‘might help ease the pressure’’ if Mr Joyce was released on bail. It made no mention of Mr Lee.

Mr Joyce and Mr Lee were released on bail after nine months in prison, but it took more than four more years until both were acquitted in November 2013 so they could return to Australia.

Mr Downer said former ministers did have to make a living, ‘‘but I didn’t make a living in this particular case’’.

While he had been offered the success fee, ‘‘it didn’t gel with me’’, he told Fairfax Media.

Mr Downer said there was also the issue of measuring how much his intervention may have played in Mr Joyce’s release.

‘‘Every success has a thousand fathers and every failure is an orphan – number one. Number two, I didn’t think it would have been ethical, honestly.’’

Mr Downer is an old boy from Geelong Grammar, the same school attended by Mr Joyce and another of his co-accused, Angus Reed. Other old boys from the school, Malcolm Fraser and Prince Charles, also helped Mr Joyce in an intensive diplomatic campaign.

Mr Joyce and Mr Lee have not spoken since 2010. Mr Lee’s legal team was keen to keep distance between their defence strategies.

Mr Joyce, who had been managing director of the Dubai Waterfront development, was convicted on bribery charges in May last year and sentenced to 10 years' jail and a $25 million fine, as was Mr Reed, who was tried in absentia. Dubai’s Court of Appeal acquitted Mr Joyce in November.

Mr Lee, who had been director of commercial operations at Dubai Waterfront, was acquitted in May last year and this was confirmed in November when he beat a prosecution appeal.