Australia Prime Minister Malcolm Turnbull has described the Malaysian authorities as being "very lenient" with the nine Australians who stripped down to their swimwear emblazoned with the Jalur Gemilang at the Sepang Formula One event over the weekend.

The Australian prime minister was responding to the Sepang Sessions Court’s decision yesterday to free the nine dubbed as the "Budgie Nine" with a warning.

According to Australian media reports, Turnbull said it was appropriate for the men to apologise in court on, and described them as "very repentant".

"They are on their way home and that's good. I think the Malaysia authorities were very lenient," he was quoted as saying.

Among the nine, who spent four days in the police lock-up, was Jack Walker, an adviser to Defence Industry Minister Christopher Pyne.

Reports said the prime minister would talk to Pyne once he returns regarding his future as a ministerial adviser.

"He needs to have a very hard look at himself and I'm sure will be considering his future carefully," Turnbull said.

Yesterday, Sepang Sessions Court judge Harith Sham Mohamed Yasin told the nine that their conduct was "totally inappropriate" and had “provoked the sensitivity of Malaysians”.

However, Harith took into account their young age.

He also took into consideration how the nine, aged between 25 and 29, were remanded for four days, had lacked awareness that their action was insensitive and that they were remorseful.

The nine earlier pleaded guilty under Section 290 of the Penal Code for public nuisance, which carries a fine not exceeding RM400.

The men were referred to as the ‘Budgie Nine’ for sporting swimwear known in Australia as budgie smugglers.

Photographs of the foreigners in the Malaysian flag swimwear had gone viral on social media.

Besides stripping down, it was reported the men drank beer out of their shoes, mimicking the actions of the winning F1 driver, fellow Australian Daniel Ricciardo, on the dais.