RCMP Cpl. Annie Linteau says investiagtors are not convinced that two tonnes of missing explosives have been accounted for. (CBC)

RCMP in B.C. say they are still not convinced that two tonnes of a potential explosive that was believed missing in a rail shipment from Alberta to Vancouver has been accounted for.

The chemical manufacturer Kinder Morgan notified the RCMP on Jan. 6 that it had determined a clerical error was responsible for the apparent loss or theft of two one-tonne bags of ammonium nitrate.

"RCMP and Natural Resources Canada investigators have since been conducting a detailed review to validate Kinder Morgan's assessment," RCMP Cpl. Annie Linteau said Friday in Vancouver.

"To date, investigators have not been able to confirm Kinder Morgan's conclusions."

A shipment of 6,000 one-tonne bags of the fertilizer ingredient was sent from Kinder Morgan's Alberta facility to a depot in North Vancouver in the fall of 2009.

Used in deadly U.S. bombing

The company called in the RCMP on Dec. 31, 2009, to report the missing bags before declaring one week later that the discrepancy had been the result of a clerical error.

A truck packed with about one tonne of ammonium nitrate was used in the Oklahoma City bombing in 1995 that killed 168 people.

The so-called Toronto 18 conspirators also reportedly sought large quantities of ammonium nitrate in order to make bombs.

Police arrested two members of the Toronto 18 group in 2006 as they unloaded what they believed were large quantities of ammonium nitrate. (CBC)

The RCMP's threat level for the Olympic Games remains at low and the force does not intend to adjust its threat level for the Games as a result of this investigation, said Linteau.

"The RCMP will continue to work diligently to determine whether any product is in fact missing, and if so, what happened to it."

No information to date shows evidence of any theft or criminal wrongdoing, she said.