Police have arrested two students in Manchester in connection with an alleged £300,000 lottery fraud.
The two men are suspected of sending thousands of emails telling recipients they had won the Canadian Lottery and persuading them to pay a fee to claim their fictitious winnings.
The men, aged 21 and 22, were at their home when officers searched the property in east Manchester on Tuesday.
Both students, who are at university in Manchester, have been released on bail.
Police said records from computers seized during the search indicated that hundreds of people had paid a total of up to £20,000 a month.
Detectives believe those responsible may also be part of a wider criminal network targeting people around the world with different mass-marketing frauds.
The raid was a joint operation by Greater Manchester Police and the City of London Police Money Laundering Unit.
Det Supt Bob Wishart, of City of London Police, said: "We believe we have uncovered a sophisticated crime perpetrated by an international organised crime group, exploiting the latest mass marketing technology on the internet to target innocent people in their homes and on their computers.
"We will continue to target those groups who choose to operate in the UK, and disrupt their activity."
Police are warning that mass-marketing frauds are becoming "more plausible and more sophisticated" and are urging people to report being targeted.