TORONTO—Sticky-fingered thieves made off with as much as 30 million Canadian dollars (US$30.4 million) worth of maple syrup from a little-known strategic reserve in rural Quebec—leaving authorities to investigate just how much is missing and where it has gone.

The Federation of Quebec Maple Syrup Producers said late Thursday that during a routine inventory check at a facility that stores some 10 million pounds of syrup, inspectors discovered barrels had been emptied and reported "missing a large quantity of maple syrup."

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