Raids mounted on fake Indian tech support centres
More than 50 people have been arrested in India for their alleged involvement in fake security warning scams.
The New York Times said that Delhi police made the arrests during raids on 26 call centres linked to the scams.
Software giant Microsoft helped police trace who was behind the large-scale operations.
It said it received more than 11,000 calls per month about fake security warnings and that many people lost significant sums to the fraudsters.
"This is an organised crime," Courtney Gregoire, an assistant general counsel in Microsoft's digital crimes unit told the US newspaper.
Microsoft has estimated that fraudsters make about $1.5bn (£1.2bn) a year through fake Windows support calls.
Raids on 16 call centres were carried out this week and, earlier in November, another 10 locations were visited by police.
The raids were prompted by Microsoft filing complaints with local police in New Delhi about call centres it claimed were involved in the fraudulent operations.
Typically, said Microsoft, attempts to trick people revolved around pop-up warnings that falsely claimed that a person's computer was infected with a virus.
Fixing the non-existent virus could involve ringing a tech support centre. An operator would talk a victim through a fake fix and then charge them for the work.
In another version of the scam, staff at call centres claimed to be calling from Windows official support saying they had spotted that a person's computer has been hacked or harboured a virus. Again, victims were expected to pay to fix the non-existent problem.
Some people caught out by the scam paid up to $1,000 for the fake tech support, said the newspaper.
Microsoft has published advice about ways to spot the fake calls and avoid becoming a victim.