The Papua New Guinea activist group, ACT NOW!, says Australia has to do more to help PNG crack down on money laundering.
This followed last week's decision by a Singapore court in which former PNG prime minister Sir Michael Somare was implicated.
The court jailed a couple for laundering US$3.6 million dollars intended for setting up community colleges in PNG.
The court also established that US$784,000 of the money was deposited in the bank account of Sir Michael Somare, who was PNG's prime minister at the time.
Sir Michael apologised for the shame caused to PNG but said at no time in his political career had he received inducements or bribes.
ACT NOW! said as much as 50% of PNG's annual government budget was stolen through a variety of different scams involving politicians, bureaucrats and private companies.
It said much of that money is believed to end up in Australia, where it is invested in property, on school fees and other living expenses or squandered in casinos.
The NGO's Eddie Tanago said they want Australia to be much more proactive in cracking down on illegal money flows out of PNG.