Image caption Maple syrup is a completely natural product made in limited quantities

Thieves in Canada have stolen millions of dollars worth of highly prized maple syrup from a storage facility, Quebec police have said.

The Federation of Quebec Maple Syrup Producers noticed that barrels supposed to contain the sugary liquid were empty after an inventory check.

The theft took place at their warehouse in St-Louis-de-Blandford, 160km (100 miles) north-east of Montreal.

Police say it is unclear exactly how much of the expensive syrup was stolen.

Some 3.4 million litres of bulk maple syrup was stored in the warehouse, with a value of up to CAN$30m (£19m).

If the entire warehouse's contents were stolen, it would represent more than a tenth of Quebec's 2012 harvest, according to CBC news.

"The St-Louis-de-Blandford warehouse had been secured by a fence and locks, and visited regularly," federation president Serge Beaulieu said in a statement.

The federation also keeps nearly 13m litres in syrup in three warehouses to stabilise global supply and prices.

"I can assure you there will be no shortage in maple syrup," Anne-Marie Granger Godbout from the Federation of Quebec Maple Syrup Producers told the Reuters news agency.

The syrup was due to be transferred to a new storage facility in the coming weeks.

Maple sap is tapped directly from the sugar maple tree and boiled to concentrate it into maple syrup. Quebec produces three quarters of the world's maple syrup.