Nigeria has recovered some $200m from conmen in the past eight months, its anti-corruption commission says.
Western businesses are often targeted by Nigerian fraudsters
Nigeria is rated the world's second most corrupt country and has become notorious for its fraudsters.
They send out letters and e-mails offering to deposit millions of dollars in bank accounts but instead they use the bank details to make withdrawals.
President Olusegun Obasanjo last week set up a special panel to fight economic crimes on the internet.
The Economic and Financial Crimes Commission (EFCC) was set up earlier this year specifically to tackle the advance fee fraud, known in Nigeria as the "419 scam".
Its chairman Nuhu Ribadu also said that 200 suspects had been arrested and 40 cases were in court.
He also said that the commission had reduced the scale of oil smuggling in the past two months.
"We are going after them and we will smoke them out to face the full wrath of the law," he said.
Nigeria is one of the world's major oil producers but the price of petrol is much lower than in neighbouring countries, so there is a huge black market in oil.