One of the nine Australian men detained in Malaysia for publicly stripping down to their underwear at a Formula One race has quit his job in cabinet minister Christopher Pyne's office.
Jack Walker tendered his resignation to the Defence Industry Minister on Saturday, shortly after returning to Australia.
"Jack Walker has today offered me his resignation and I have accepted it," Mr Pyne said in a statement.
"Jack indicated to me his deep regret for causing any embarrassment to the government and apologised.
"One lapse of judgement does not detract from the fact that Jack has been an outstanding staff member, a significant contributor to my office since late 2013 and I believe he will have a bright future."
Mr Walker, a 26-year-old policy adviser, dropped his daks alongside eight friends at the Grand Prix in Sepang last Sunday, revealing budgie smugglers emblazoned with the Malaysian flag.
They chanted "Aussie Aussie Aussie, oi oi oi" for several minutes and wrapped themselves in Australian flags as they stood in the middle of a crowd, celebrating Daniel Ricciardo's win.
They then poured beer into their shoes and drank from them – mimicking Ricciardo on the dais.
Authorities in the conservative Muslim nation took a dim view of their behaviour and the men spent four nights in a Malaysian jail cell before being cautioned and released.
The men wasted no time boarding flights back to Australia.
Mr Walker flew in to Perth from Kuala Lumpur on Friday with his father John Walker. He refused to comment except to say he was "happy to be back".
Prior to working for Mr Pyne, Mr Walker worked for NSW Liberal Party powerbroker Michael Photios' lobbying firm.
Branden Stobbs, 29, Edward Leaney, 25, Nicolas Kelly, 27, Thomas Laslett, 28, Thomas Whitworth, 28, James Paver, 27, Adam Pasfield, 25 and Timothy Yates, 29, also arrived home on Friday.
Mr Walker's resignation came after Prime Minister Malcolm Turnbull said he needed to have a "very hard look at himself".
"I am sure he will be considering his future carefully," Mr Turnbull said.
"I think the Malaysian authorities were very lenient and I think the young Australian men were very repentant but they do need to reflect very seriously on their conduct," he said.
