University of Alberta math professor Andrew Liu is among 341 people charged as part of a global child-exploitation investigation initiated by Toronto police.

Liu, 66, was charged with possession of child pornography after police searched his downtown apartment on Oct. 23.

"Our investigation is ongoing ... and items seized from the residence  are still being analyzed, so as far as numbers (of items) I can't say," said Sgt. Mike Lokken with the Alberta Law Enforcement Response Teams.

CBC News has learned Liu is accused of possessing child porn from as far back as May 2007. Liu is free on bail while awaiting a court appearance on Dec. 20.

The university was not willing to respond to the charges.

"He is a retired professor with a part time post-retirement teaching contract," said spokesperson Deb Hammacher in a prepared statement. "He's not currently teaching and is not scheduled to do so at this time."

Two men in Calgary were also charged in the bust. Police said 50 of those arrested are from Ontario and 58 are from other parts of Canada.

Police also said the investigation led to the rescue of 386 children from child exploitation

The investigation began following an arrest in Toronto in May 2011. At the centre of the bust is Azov Films, a Toronto company that police believe sold videos of naked boys, through DVD orders and online.

ALERT was one of 38 police agencies from around the world involved in the investigation.