PETALING JAYA: The Jalur Gemilang-themed underwear worn by a group of men at the Formula 1 Petronas Grand Prix on Sunday come from an Australian swimwear label and are available online.

Checks revealed that the briefs, made with polyester fabric with the Malaysian flag design, cost AUD$55 (RM174) on the label's online store.

Besides the Malaysian flag design, there are also briefs adorned with flags from Brazil, the United States, France, Sweden and Japan, among others.

For reasons unknown, the Malaysian flag design is not available for purchase at the time of writing.

On Sunday, a group of nine Australians, aged between 25 and 29, disrobed and revealed their briefs to spectators at the Sepang International Circuit (SIC).

The group were detained at 5pm on the same day shortly after the incident.

They are being remanded for four days to facilitate investigations.

The case is being probed for provocation and public indecency.