KUALA LUMPUR, Oct 9 — A policy advisor to an Australian minister has resigned after he and eight other Australian men caused an international row by stripping to their swimming trunks in Malaysia.

ABC News reported today that Jack Walker, 26, gave notice to Defence Industry Minister Christopher Pyne on Saturday, shortly after he flew back to Australia.

"Jack indicated to me his deep regret for causing any embarrassment to the government and apologised,” Pyne was quoted saying.

"One lapse of judgment 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,” he added.

Sessions Court judge Harith Sham Mohamed Yasin on Thursday invoked an infrequently used legal provision to avoid passing down any sentence to the nine men, who removed all their clothing save for briefs printed with the Malaysian flag during the Formula One Grand Prix here last week.

Harith’s decision also meant that none of the group would have criminal convictions on their record. The nine, aged between 25 and 29, had pleaded guilty to charges of public nuisance.