It was only the second time that the international police agency has appealed directly to the public for help in identifying a suspected pedophile. The first time, last October, rapidly led to an arrest.
The suspect in the latest case is a white man, shown with gray, thinning hair in six photos released by Interpol. He appeared to be in his late 40s or early 50s in the images.
Interpol said that despite two years of investigations, it and other police agencies have so far been unable to determine his identity, nationality or whereabouts - hence the decision to appeal publicly for information.
"The law enforcement community around the world has done all it can to find this man who clearly presents a danger to young children, and we are now asking the public to help identify this predator and protect other potential victims from abuse," Interpol Secretary General Ronald Noble said in a statement.
In interviews at the agency's headquarters in Lyon, France, Interpol officials said they had recovered photos of the man that allegedly show him sexually abusing at least three boys, apparently aged between 6 and 10 years old. The boys appear to be from Southeast Asia - though Interpol officials declined to specify any possible countries.
Kristin Kvigne, assistant director of Interpol's division that combats people trafficking, said it was impossible to know how many other children the man could have abused.
"There are at least three child victims that are in the images, but it could be more," she said in an interview.
Kvigne said the photos show "severe abuse" by the man but she declined to go into detail.
Two graphic photos seen by The Associated Press, which were not among those that Interpol made public, appeared to show the man engaged in fellatio with a tanned thin boy. In another, the man was lying between two boys who appeared to be touching his genitals.
"It's important to know that these images were found on the Internet, so the attention that he is going to draw is attention that he actually put on himself when perpetrating against children," Kvigne said.
Interpol said it believes that the photos were taken between April 2000 and May 2001.
Police first became aware of the suspect in March 2006, when photos of him were found on the computer hard-drive of a man arrested in Norway who was later convicted on pedophilia-related charges, Interpol said.
Police then cross-checked those photos against others found on the Internet, to see if there were matches that might link the man to other alleged abuse. Interpol used its database of child abuse images to perform the checks, scanning such details as the wallpaper shown in photos to see if there were matches. In all, Interpol said that it found about 800 photos featuring the man, his alleged victims, or areas where they were once pictured.
One of the photos released publicly by Interpol shows the man wearing glasses. Two others show him lying on a checkered mat or rug in a plaid, yellow shirt. None of the six photos show him with boys - though one appears to show what looks like the side of a boy's shoulder, and a small tuft of hair.
In October, suspected pedophile Christopher Paul Neil, a 32-year-old teacher from Canada, was arrested in Thailand just 11 days after Interpol issued a global appeal to help apprehend him.
In that case, Neil's face had originally been disguised in Internet photos with a digital swirl. Police managed to reverse the swirl process, unmasking his face, and Interpol released those cleaned-up images publicly. Neil was arrested in Thailand on Oct. 19, 2007. He went on trial in March, accused of sexually abusing a 9-year-old boy.
In the latest case, the man did not appear to make any effort to hide his identity on the photos that were seized on the computer in Norway, Interpol officials said.
Interpol officials said they don't know why the man did not attempt to disguise his face in photos showing alleged abuse. But officials noted that pedophile offenders sometimes reveal their identities to win trust in child-sex offender circles, in hopes of getting access to other children or images.
Kvigne said Interpol was "very careful" in weighing the decision to launch the appeal. She said it was a "powerful tool" that should be reserved for only a limited number of cases.
"Our main concern is of course the safety of children," she said.
Among the risks, she said, are that an innocent person might be incorrectly identified, "and that's why we encourage people to call police if they believe they know who this man is."
She said people should contact their local police or Interpol, "but to take no action on their own." She also said she hoped the man would come forward to police himself.