Hundreds of Irish people have been caught up in a major international investigation into the illegal downloading of child pornography, the Sunday Tribune has learned. It is understood that in excess of 300 Irish people either viewed or downloaded explicit images of child pornography involving babies and young children from a Croatian-based website.

Gardaí have been liaising with Interpol on an ongoing basis and dozens of raids have taken place over the past few weeks as part of the operation, which is codenamed Bonfire.

Home computers and laptops have been seized and are in the process of being technically examined by garda experts.

It is understood that the homes of a significant number of middle-class professionals with wives and children have been targeted after their computers were linked to the illegal website. Sources say they expect a number of prosecutions to reach the courts.

Senior garda sources say that Interpol has provided officers with at least 300 unique IP addresses of Irish computers.

The operation dwarfs the previous biggest garda investigation involving child pornography. More than 100 premises were raided as part of Operation Amethyst in 1999 following information received from the FBI.

The majority of the addresses in Operation Bonfire are based in Dublin, but dozens of people from outside the capital also viewed the material.

In August 2007, the website of a legitimate Croatian astronomy business was hacked into from somewhere in northern Europe and 99 pornographic photographs of children were posted.

In the course of just 76 hours, the website, which traditionally encountered little traffic, recorded 12 million visits to the pages containing the photographs.

The volume of visits can be explained by the fact that a link to the web page was broadcast across internet paedophile networks.

After analysis from Interpol experts in November of last year it was determined that 144,285 unique computers from 170 countries had either

viewed or downloaded the material. The intelligence gathered by Interpol was unable to determine whether the Irish suspects viewed or downloaded the material.

If a person accidentally stumbled upon the illegal images and immediately shut down the site, then this would mean that they would not be prosecuted. However, downloading the images is illegal and would result in a prosecution. Gardaí who have seen the images say they are deeply disturbing and involve very young children.

The garda operation is being headed by detectives from the Domestic Violence and Sexual Assault Investigation Unit (DVSAIU), which is attached to the National Bureau of Criminal Investigation in Harcourt Street.

The DVSAIU has received the IP addresses from the Dublin Interpol office at Garda Headquarters and, over the last several months, has been in the process of tracing the addresses and giving them to local detectives to investigate. An IP address is a type of fingerprint unique to each computer which enables computers to identify and communicate with each other across networks.

In order to secure warrants to enter the premises and seize computers, a senior garda is required to appear before a district court to get the permission of a judge.

The Sunday Tribune understands that there is a significant backlog in the garda computer forensic unit which analyses the material viewed and downloaded by suspect's a computer.

Unless the case is listed as a priority or involves children, it can take up to a year to have the computer examined. It is likely that computers from Operation Bonfire will be given priority, but because of the number involved, it will take many months to forensically examine each machine.

A spokeswoman for the An Garda Siochana told the Sunday Tribune that because the garda operation is ongoing she was not in a position to comment on any aspect of the story.