Police in Denmark, Finland, Norway and Sweden conducted a series of coordinated raids on suspected pedophiles on Tuesday, and the media reported the arrest of at least 100 people.
Hundreds of police officers took part in the swoop, which began at 6:00 am (0400 GMT) and which targeted people "suspected of possessing documents portraying sexual abuse against children", Norway's criminal police Kripos said in a statement.
A Kripos spokesman refused to provide any further details about the raids pending a press conference later Tuesday.
"We will make no comment as long as the operation is still underway so as not to hinder its efficiency," spokesman Jan Tore Knutsen told AFP.
Swedish news agency TT meanwhile reported that some 100 people had been arrested in Sweden alone and that computers and other equipment had been seized. Police, who traced the suspects with credit card numbers they had used to buy child pornography over the Internet, said there was nothing to indicate so far that the suspects had produced child pornography themselves.
"But we don't yet have an overview of the results of the operation yet, for example we don't know how many have confessed," one police officer said. In Denmark, 43 people were arrested and computer equipment was also seized, Danish police official Soeren Thomasson told AFP.
Pedophiles in Denmark face fines or prison sentences of two to six years.
"The people arrested are currently being questioned and it is still too early to say whether they will be released or go before a judge before being placed in temporary custody," Thomasson said.
AFP