WASHINGTON – Nearly every internet user has received e-mail appeals from what are known as the "Yahoo boys," scam artists residing in West Africa.

There is the "Nigerian prince" fraud, in which the author of an e-mail says he wants to transfer a large sum of money and would kindly compensate the recipient for aiding in the transfer. But first, the recipient must pay various fees, which end up being sizable. No large sum of cash ever materializes.

Then there is the "stranded traveler" fraud, in which a fraudster takes control of an e-mail account, impersonates the account's owner and asks all contacts to provide help since he or she has been robbed at gunpoint overseas. Immediate monetary assistance is sought.

Such scams may seem penny ante compared to the sophisticated ransomware attacks coming from Eastern European cybercrime gangs. But a new report released Thursday indicates that West Africa is becoming a significant hub of global cybercrime.

Cybercrime-related complaints in West Africa soared from 940 in 2013 to 2,182 in 2015, said "Cybercrime in West Africa," a report jointly done by the global police network known as Interpol and Trend Micro, a security software company with headquarters in Tokyo. Only 30 percent of the cybercrimes reported to police in the region lead to arrests, it said.

A survey preceding the report was conducted in 11 of the 16 countries that compose the region, the largest and most populous of which is Nigeria.

The report notes a cultural mind-set in West Africa that is forgiving of fraud, "equating it to outsmarting victims, especially foreigners." Recruitment into the gangs is easy. Fully half of university graduates in the region do not find employment, it said.

The Yahoo boys got that name because of their heavy use of Yahoo apps for communication via e-mail and instant messaging, the report says. Gangs run several different types of fraud at once.

"They can, for instance, run a romance fraud with one victim and an advance-fee fraud with another while sending a stranded-traveler fraud e-mail to other potential victims," it said.

Above the Yahoo boys are a new breed of what the report calls "next-level cybercriminals" who engage in more complex fraud, often worming their way into corporate networks and sending requests to internal finance offices for matters like legal settlement fees, funds for "secret" deals and emergency salary advances, the report said.

"FBI reports show that between October 2013 and May 2016 alone, more than $3 billion was stolen by (business e-mail compromise) fraudsters," the report said.

It said that West African cybercriminals usually operate in tight-knit groups and "are clearly shifting to more elaborate crimes, complex operations and business models." "We believe they will continue down this track and soon become as sophisticated and innovative as cybercriminals in other countries and regions," the report said.