Police have conducted raids in six European countries and detained up to 30 people to crack a child pornography ring that shared abusive images over the Internet, officials said Wednesday.

Rome's Carabinieri paramilitary police (search), who led the operation, said about 80 people had been placed under investigation and computers, DVDs, CD-ROMs, video tapes and memory cards for digital cameras were seized in raids in Italy, Denmark, France, the Netherlands, Sweden and Britain.

The suspects had created a secure network that allowed them to use the Internet to anonymously share pornographic images of children aged 11 and under, the Carabinieri said in a statement.

The statement said those being investigated in Italy were all men aged between 25 and 65, were concentrated in the center and north of the country, and included doctors, information technology workers and photographers.

In France, police seized computer hard drives and detained 20 people in raids around the cities of Versailles, Orleans, Bordeaux, Lyon, Marseille, Rennes and Strasbourg, officials said.

Denmark's National Police (search) said up to 10 people there have been detained as part of the investigation, while Swedish police spokeswoman Annethe Ahlenius said 42 people were "subject to investigation" in Sweden in connection with the raids.

The Dutch raids were on houses in the municipalities of Middelburg and Maastricht, both in the south of the country. Dutch, Italian, and Swedish police said no arrests had been made in their countries.

European police agency Europol, which helped coordinate the operation, said police in Rome had provided the initial intelligence based on Internet boards whose members possessed and distributed child abuse material.

The networks used sophisticated techniques to hide the electronic identities of members and to encrypt their communication, Europol said in a statement.

"It is important to show the persons, who directly or indirectly are involved in a sexual abuse depriving children of their childhood, that they cannot stay anonymous behind a computer screen," said Europol Director Max-Peter Ratzel (search) said.

"The perpetrators have to realize that they cannot feel safe if they deal with child pornography," he said.

Europol said that due to the lengthy process required for computer and storage device analysis, national investigations in the countries involved are ongoing.

A previous phase of the investigation, codenamed "Ice Breaker," led to the arrest of 25 people in 13 European countries in June.