LONDON — A team of international investigators infiltrated an Internet chat room used by pedophiles, rescuing 31 children and identifying more than 700 suspects worldwide.

Undercover officers in Britain, the U.S., Canada and Australia busted up the pedophile ring using surveillance techniques more commonly associated with fighting terrorism and organized crime.

The chat room, which was called "Kids the Light of Our Lives," featured images of children being subjected to abuse, said Jim Gamble, chief executive of Britain's Child Exploitation and Online Protection Center.

Police analyzed images and videos traded by the chat room's members for the smallest clues that could help them identify, locate and rescue the victims.

More than 15 children were found in Britain, Gamble said, declining to give further details.

A Canadian official said authorities there arrested 24 Canadians and rescued seven Canadian children as part of the probe. Four people have been arrested in Australia.

Describing it as "a massive leap forward," Gamble said the investigation involved agencies from 35 countries. Investigators made the case public after the sentencing of ringleader Timothy David Martyn Cox on Monday.

Cox, 27, was given an indeterminate jail sentence, meaning he will remain in prison until authorities decide he is no longer a threat to children.

The probe began in Canada in the spring of 2005, then expanded internationally in August 2006 after Canadian officials tipped off authorities in London that they believed the chat room's host was based in Britain.