Norway's National Criminal Investigation Service (Kripos) raided the homes of scores of suspects on Wednesday morning, seizing 173 computers and 469 storage devices which have since been found to hold some 600,000 images of children.
"Now, 29 hours after the operation began, we have questioned and charged 73 people. Forty-four of these have admitted guilt," the Kripos's Bjørn-Erik Ludvigsen said in a press conference on Thursday.
Many of the people to be charged, who were all users of the file-sharing network eDonkey2000, had been previously convicted of abusing children.
"In about 30 percent of the cases, those who are suspected of or charged with distributing images are also physical abusers," said Lena Reif, head of the NCIS's sexual crime unit.
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None have yet been formally charged.