In coordinated swoops late last month, local and international authorities searched houses and seized hundreds of devices containing child sexual exploitation material in South and Central America as well as Germany, Italy and Spain, Europe's policing agency Europol said in a statement.
"These offenders are pushing the boundaries of modern technology to try to avoid being caught by law enforcement," Europol's director Rob Wainwright said.
Dubbed "Operation Tantalio", the investigation was sparked in mid-2016 by the Spanish police's High-Tech Crime Unit focusing on the Tor encryption network, used by criminals to mask their identities.
"Prompted by clear evidence of prolific sharing of indecent images, the Spanish investigators revealed links diverting users to private groups on WhatsApp," Europol said.
A total of 25 groups, formed by invitation only, are currently being investigated, according to Europol.
"We need to continue to combine our joint resources and skills to tackle this threat to our children and bring these offenders to justice," Mr Wainwright said.
"Actions like Operation Tantalio send a strong message" that police across the globe will continue to work together to bring to justice those "engaging in or benefitting from the heinous crimes," added Bjorn Sellstrom, Interpol Crimes Against Children operations coordinator.