Image caption Officials said that many of the images appeared to show children in Canada and North America

Twenty one people have been arrested in Canada as part of a nationwide child pornography investigation, the Royal Canadian Mounted Police say.

Hundreds of thousands of images were found on more than 100 computers and 1,000 discs as part of Operation Snapshot, officials said.

A 14-year-old boy was also rescued during the months-long investigation.

RCMP officials said the arrests had not broken a child pornography ring but instead were independent cases.

Sixteen of those arrested have been charged with various crimes, including sexual assault and the making and distribution of child pornography. More charges are pending, police said.

Beginning in June, the RCMP and six police forces across Canada identified suspects who possessed and distributed child abuse images across peer-to-peer file-sharing networks.

Det Sgt Darren Parisien, who headed up the operation, told reporters that most of the images were of children under the age of 12, including pictures of infants and toddlers.

"We try to identify and locate every child in every picture and video we can," Det Sgt Parisien said, adding that many of the images did not appear to be from other countries.

"Most of the images that we're seeing now are homegrown."

The 14-year-old boy rescued in Saskatoon, Saskatchewan had been abused by a family member's friend for about five years, police said. One man has already been convicted in the case.