Nigeria's finance minister has pledged to crack down on the country's notorious e-mail fraud schemes.
Ngozi Okonjo-Iweala: Don't respond to '419' e-mails
Ngozi Okonjo-Iweala said her government was planning "decisive" action against the scams, which dupe thousands of foreign businessmen every year.
"We are absolutely determined to move," she told BBC World Service business reporter Rodney Smith.
Ms Okonjo-Iweala said the authorities had recently arrested three of the "kingpins" behind the scams.
The Nigerian government had set up a committee to draw up ways of tackling the problem, and was also planning a fresh advertising campaign to deter would-be fraudsters, she said.
The fraudulent letters and e-mails, sent from Nigeria to businesses around the world, purport to come from senior Nigerian officials asking for help in channelling stolen funds offshore.
In one common version of the scam, the recipients are invited to pay advance 'fees' to cover costs associated with transferring the money abroad.
A 2001 report from the UK's National Criminal Intelligence Service estimated that the scam - known as the 419 Advanced Fee Fraud, after the section of the Nigerian penal code which covers the crime - was costing British businesses up to £150m a year.
Nigeria has been trying to stamp out the fraud for years, but its perpertrators have often avoided detection by abandoning traditional letters in favour of e-mail.
"I think even the developed countries are struggling with how to police internet crime, and we are struggling too," Ms Okonjo-Iweala said.
"We would like any assistance to help us do this."
She urged those who received 419 letters or e-mails to ignore them.
"I ask people who get these letters to absolutely not respond to them," she said.
"There is no free lunch, and the idea that you just pay a little bit here, and you are going to get a lot out of it, is just not tenable."
Speaking at the World Economic Forum in Davos, the Nigerian finance minister also defended controversial import restrictions imposed earlier this month by her government.
She said the measures, which affect products including textiles and pork, came in response to "unfair" competition, and were compatible with WTO rules.
"I think it's a bit hypocritical when you have developed countries that have all sorts of tariffs on steel and other products ... and when a little thing happens like import restrictions on toothpicks and textiles, people start saying they're irritated."