Fraudsters have tried to dupe money out of the very organisation charged with stamping out the scam in Australia.

You will never make any money out of this offer Michael Dunn Asic

Financial regulators in Sydney estimate con artists have got away with more than $5bn from people around the world who responded to get-rich-quick letters from Nigeria.

So when they received their own e-mails offering a slice of $440m, they knew not to add to the profits.

"It's a scam and we know it," said Michael Dunn, the consumer communication director of the Australian Securities and Investment Commission (Asic).

Potential victims are sent letters, e-mails or faxes purportedly from someone with close links to the Nigerian Government or business community.

NIGERIAN LETTER SCAM

The set-up: Help move cash or commodity out of Nigeria for cash reward Simply provide bank details to facilitate reward payment The sting: Advance "fees" demanded Bank accounts accessed and emptied

The writer promises a reward for help in moving cash or another commodity and asks for bank-account details to ensure the "hitch-free transfer" of payment.

But Mr Dunn - who has himself received 11 Nigerian e-mails in the last three weeks - said: "You will never make any money out of this offer."

Once respondents get involved, they are asked to pay "advance fees" for customs, taxes and bribes, the commission said.

These fees - often adding up to tens of thousands of dollars - are the real purpose of the scam.

Warnings

And if people do not pay, the fraudsters access victims' bank accounts and drain them of every cent, the commission said.

"Asic is issuing warnings about this scam because even though it's well-known, people are still getting ripped off," Mr Dunn said.

Governments around the world as well as Nigerian authorities have so far been unable to stop the fraud.

Mr Dunn urged Australians to keep their bank account details private and only to invest with licensed financial service businesses.

"That way, you're protected under Australian law if something goes wrong," he said.

"Whereas with unregulated overseas offers like Nigerian letters, you're entirely on your own."