A group of nine Australian tourists were arrested after stripping down to their pants during the Malaysian Grand Prix at the weekend.
Photographs of the men wearing underpants bearing the Malaysian flag were widely shared on social media but have upset the Muslim community.
The men, aged between 25 and 29, were widely criticised on Twitter for insulting the country.
They were detained on Sunday and will be held for four days at a facility outside Kuala Lumpur.
Police are investigating them for public indecency and disrespecting the national flag, and a possible breach of the peace.
Malaysia has strict rules on public indecency and issues heavy fines and jail sentences.
