TORONTO — Microsoft and Canadian authorities yesterday launched a software program designed to help police worldwide hunt down child-porn traffickers by enabling authorities for the first time to link information such as credit-card purchases, Internet chat-room messages and arrest records.

Microsoft said the Child Exploitation Tracking System is the first software designed specifically to capture pornographers who prey on children and sell their images via the Internet. It will allow police departments worldwide to share and track previously unlinked information on investigations and suspects.

David Hemler, president of Microsoft Canada, said Internet pornographers were computer-savvy, so the program would put law-enforcement officials "on the same level as the bad guys."

The open-source program was developed by Microsoft Canada, the Royal Canadian Mounted Police and Toronto police, with the help of the U.S. Department of Homeland Security, Scotland Yard and Interpol.

The FBI has seen a 2,000 percent increase in the number of child-pornography images on the Internet since 1996, and Canadian police estimate that more than 100,000 Web sites contain images of child sexual abuse. Experts say at least 95 percent of victims are abused by someone they know, either a relative or neighbor.

Hemler said that Microsoft committed $4 million toward the program and that the software would be available to any police force at no cost.

The initiative was the result of a January 2003 e-mail sent to Microsoft Chairman Bill Gates from a member of the Toronto Police Service sex-crimes unit, asking for help in battling child pornography. The billionaire, known for his philanthropy in the area of AIDS research and education, called on Microsoft Canada to develop software that would aid police officials.

Detective Sgt. Paul Gillespie, who sent the initial e-mail, said several suspected pornographers already had been arrested. One man was arrested in Toronto last week, after a tip plugged into the system linked with two previous reports on the suspect.

"When we pulled up all three, it gave us the ability to physically identify somebody and grounds for an arrest warrant," Gillespie said.