Nigeria's anti-fraud police, the Economic and Financial Crimes Commission, says it has intercepted more than 15,000 fake checks in a covert operation at the main mail sorting center in Lagos. For VOA, Gilbert da Costa in Abuja reports that U.S and British investigators were involved in the month-long crackdown.

The EFCC says U.S. and British security officials were involved in the screening of tons of outward bound mail in search of fraudulent documents sent by Nigerian conmen.

Commission spokesman Osita Nwajah says the crackdown was a huge success and the partnership with Western law enforcement agencies will continue.

"This is just one level of co-operation we have with major law enforcement agencies around the world. We have been partnering with them on money laundering issues, on cyber crimes; the regular 419 issues, terrorism financing," he said. "And so this is just one layer of co-operation and this particular one will continue."

The so-called 419 fraudsters, named after the relevant section of Nigeria's criminal law, send people e-mails seeking to trick them into handing over bank details or making advance payments for non-existent money-making schemes.

Nwajah says the EFCC, which was created in 2003 has made the country very uncomfortable for conmen, who are now shifting operations to neighboring countries.

"One of the challenges is that some of these people have fled the physical space of Nigeria," added Nwajah. "You now find them in neighboring countries that do not have a strict regime, as we have in Nigeria, of enforcement. So, there is this tendency for them [fraudsters] to settle in. We are pursuing them across the border by co-operating with law enforcement agencies in neighboring West African states."

President Umaru Yar'Adua who took power in April has pledged to clean up the reputation of Africa's largest democracy, which is tarnished by endemic corruption and fraud.