The Correctional Service of Canada is investigating how dozens of personal prison items from British Columbia serial killer Clifford Olson wound up for sale in an online auction.

Public Safety Minister Stockwell Day is asking the CSC's commissioner to look into the case - and has ordered a probe into how the material left the prison.

Up for auction is a large lot of letters, prison forms and personal items - including pornographic magazines - belonging to Canada's most notorious child killer.

The items are being sold through a U.S.-based website called Murder Auction.

The Australia-based online seller, known only as nrs24985, says he was able to gain access to the items while corresponding with Olson over a two-year period.

"This collection of letters (was) sent to members of my family, during my correspondence with the killer that ended abruptly last year," writes the seller on the auction site.

The seller also writes that Clifford Olson boasted to him about "having inside knowledge of the 9/11 terrorist attacks from being pen pals with the terrorists" and also that Olson knew other serial killers - including B.C.'s Robert "Willie" Pickton and the man dubbed the Green River killer, Gary Ridgway.

Murder Auction is currently selling hundreds of personal items once belonging to convicted serial killers, including prison greetings from Jeffrey Dahmer - and DVD copies from the 2007 parole proceedings of Charles Manson.

There are also prison documents signed by Coquitlam, B.C., killer Robert "Willie" Pickton.

In a written statement, Public Safety office spokesperson Melisa Leclerc, says Minister Day `is concerned with the fact that an individual would consider making profit out of a heinous crime.'

Leclerc added that Corrections Canada has the legal authority to restrict publications or other works created by inmates.

Olson, now 68, is serving life prison sentence for killing 11 children and teenagers in British Columbia in the early 1980's.

Leclerc says once the results of the investigation are completed, Minister Day will discuss options with federal CSC Commissioner Don Head about how to prevent this situation from happening again.