The Australian Tax Office (ATO) is investigating more than 800 individual taxpayers, all residents of Australia.
They have been identified as high net wealth clients of a law firm in Panama.
The investigation follows a leak of 11m documents from the database of law firm Mossack Fonseca, revealing how wealthy and powerful people hide their wealth.
The ATO says in a statement it has managed to link more than 120 of the individuals to an “associate offshore service provider” located in Hong Kong.
The tax body did not disclose the name of the company in Hong Kong.
The ATO is working closely with the Australian Federal Police, Australian Crime Commission and other agencies, and said some cases may be referred to the Serious Financial Crime Taskforce.
“The message is clear – taxpayers can’t rely on these secret arrangements being kept secret and we will act on any information that is provided to us,” said ATO Deputy Commissioner Michael Cranston.