Air Canada has fired back in a lawsuit by security firm Brinks, saying the airline bears no responsibility for the daring theft of $23.8 million in gold and cash from its facilities at Torontos Pearson airport earlier this year.

A thief walked walked away with the costly cargo after presenting a phoney document at an Air Canada warehouse on April 17, according to the Brinks filing last month.

In a Nov. 8 statement of defence, Air Canada rejected each and every allegation in the Brinks suit, saying it fulfilled its carriage contracts and denying any improper or careless conduct.

The countrys largest airline goes on to say that Brinks failed to note the value of the haul on the waybill -- a document typically issued by a carrier with details of the shipment -- and that if Brinks did suffer losses, a multilateral treaty known as the Montreal Convention would cap Air Canadas liability.

Brinks Switzerland Ltd. elected for its own reasons not to declare a value for carriage and to pay the standard rate for the AC Secure services product and, to Air Canadas knowledge, elected not to insure these shipments, the Air Canada filing reads, adding that Brinks was fully aware of the consequences.

In Federal Court filings last month that claim breach of contract and millions of dollars in damages, Brinks said an unidentified individual gained access to the airlines cargo warehouse and presented a fraudulent waybill shortly after an Air Canada flight from Zurich landed at Pearson.

The statement of claim says staff then handed over 400 kilograms of gold in the form of 24 bars -- currently worth about $21.1 million -- plus nearly US$2 million in cash to the thief, who promptly absconded with the cargo.

Even the cash -- it converts to nearly $2.7 million Canadian -- weighed a bundle, with the banknotes registering more than 53 kilograms.

The suit claims Air Canada was negligent and failed to follow through on appropriate security measures to prevent theft of the goods.

A pair of Swiss companies -- precious metals refinery Valcambi SA and retail bank Raiffeisen Schweiz -- contracted Brinks to provide security and logistics for the shipment and compensate them for any losses, according to the Brinks suit. The gold was bound for Toronto-Dominion Bank, while the cash was en route to the Vancouver Bullion and Currency Exchange.

Brinks arranged in mid-April for Air Canada to haul the cargo to Toronto from Switzerland. It was delivered at Pearson just before 4 p.m. on a drizzly Monday, deposited at a glass-walled Air Canada warehouse on site at 5:50 p.m. and retrieved by the mysterious thief, who showed up 42 minutes later, the filings state.

Because Brinks failed to pay an extra fee or a make a special declaration of interest in delivery, Air Canada is not liable for losses, the statement of defence claims, citing the Montreal Convention, which applies to international flights.

However, the Brinks filing argues that it did pay a premium and the waybills were clearly marked as banknotes and goldbars, on top of a warning on the paperwork: Special supervision is requested. Valuable cargo. The Montreal Convention thus imposes no ceiling on the sum it can recover from the carrier, according to Brinks.

A police investigation is ongoing, with no arrests so far and the shipments still missing.