The Australian Taxation Office is investigating 800 Australians named in the more than 11 million documents leaked from secretive Panama-based law firm Mossack Fonseca, but ABC investigative journalist Marian Wilkinson says there could be more.

Some Australian banks were also involved but the material on them was fragmented.

“It was difficult to discover the documentation we needed to find out exactly what was going on,” she told the inquiry into corporate tax avoidance on Thursday.

“It will be interesting to see whether the ATO has got further with that.”

Wilkinson says more Australians could be revealed when the International Consortium of Investigative Journalists next month uploads details of all the offshore identities, more than 200,000 companies, named in the papers.

“I don’t think you can simply state that the 800 is it,” she said.

Some Australians named in the papers are convicted criminals and long-time targets of the Wickenby taskforce.

But Wilkinson says most are probably involved in legal activity, which raises questions about whether the laws need to be tightened.

Australia’s regulatory system was far better than those of Latin America or southeast Asia but “no one doubts from looking at this material, including I’m sure the ATO, that much more needs to be done”.

The leaks were revealed when an anonymous source contacted a journalist at a German newspaper.

The newspaper asked the ICIJ to contact members around the world to help analyse what has been described as the biggest data leak in history.

AAP