The Mounties have charged a Quebec youth after the user names, passwords and credit-card information from some of Bell Canada's small-business customers were posted online.
The RCMP say they started investigating after one of Bell's third-party IT suppliers was cyber-hacked.
As a result of the hacking, investigators say, 22,421 user names and passwords and five valid credit-card numbers were displayed for anyone to see on the Internet.
The youth, who cannot be identified because of his age, was arrested at a Bagotville, Que., residence early Friday and charged with one count of unauthorized use of a computer and two counts of mischief in relation to data.
Police said he is believed to be a member of a hacktivist group NullCrew, alleged to be responsible for hacking into computers of businesses, schools and government agencies.
The youth is scheduled to appear in Ottawa court Aug. 19.
Investigators had help with their investigation from south of the border, said Supt. Dean Buzza, the officer in charge of the RCMP's specialized operational services.
"Co-operation with our FBI counterparts permitted us to pursue this investigation, which ultimately led to identifying a Canadian suspect," said Buzza.
"This demonstrates yet again the importance of law enforcement working together to fight cybercrime."
The allegations against the youth have not been proven in court.