LAGOS, Nigeria — Day in, day out, a strapping, amiable 24-year-old who calls himself Kele B. heads to an Internet cafe, hunkers down at a computer and casts his net upon the cyber-waters.

Blithely oblivious to signs on the walls and desks warning of the penalties for Internet fraud, he has sent out tens of thousands of e-mails telling recipients they have won about $6.4 million in a bogus British government "Internet lottery."

"Congratulation! You Are Our Lucky Winner!" it says.

So far, Kele says, he has had only one response. But he says it paid off handsomely. An American took the bait, he says, and coughed up "fees" and "taxes" of more than $5,000, never to hear from Kele again.

Festac Town, a district of Lagos where the scammers ply their schemes, has become notorious for "419 scams," named for the section of the Nigerian penal code that outlaws them.

In Festac Town, an entire community of scammers overnights on the Internet. By day they flaunt their smart clothes and cars and hang around the Internet cafes, trading stories about successful cons and near misses, and hatching new plots.

Festac Town is where communication specialists operating underground sell foreign telephone lines over which a scammer can purport to be calling from any city in the world. Here lurk master forgers and purveyors of such software as "e-mail extractors," which can harvest e-mail addresses by the millions.

Now, however, a three-year-old crackdown is yielding results, Nigerian authorities say.

Nuhu Ribadu, head of the Economic and Financial Crimes Commission, says cash and assets worth more than $700 million were recovered from suspects between May 2003 and June 2004.

More than 500 suspects have been arrested, more than 100 cases are before the courts and 500 others are under investigation, he said.

Why Nigeria? There are many theories.

The nation of 130 million, Africa's most populous, is well educated, and English, the lingua franca of the scam industry, is the official language.

"We reached a point when law enforcement and regulatory agencies seemed nonexistent. But the stance of the present administration has started changing that," said Ribadu, the scam-busting chief.

President Olusegun Obasanjo is winning U.S. praise for his crackdown. Interpol, the FBI and other Western law enforcement agencies have stepped in to help, says police spokesman Emmanuel Ighodalo, and Nigerian police have received equipment and Western training in combating Internet crime and money-laundering.