The man behind a decade-old maple syrup heist will have to pay a C$9m (€6.5m) fine, Canada's top court has said, upholding an earlier ruling by a lower court.

A group of people in the province of Quebec siphoned off maple syrup worth over C$18 million from a reservoir and replaced it with water, before authorities discovered the robbery in 2012, in what has been dubbed the "great Canadian maple syrup heist".

Richard Vallieres, who was among the 16 people arrested by police, was found guilty of fraud, trafficking and theft and sentenced to eight years in prison and fined over C$9m by the Quebec Superior Court.

Vallieres had successfully appealed that ruling, getting his fine lowered to about C$1m - the amount Vallieres says he profited from the robbery.

However, Canada's Chief Supreme Court Justice Richard Wagner said that a court cannot limit the amount of a fine to the profit made by an offender and gave Vallieres ten years to pay the fine or serve six years in prison.

Julie Giroux, the lawyer representing Vallieres, said her client was disappointed by the court's decision to restore the initial amount imposed by the first judge and the gravity of having to bear such a substantial fine.

While the value of the stolen amber condiment was much higher, Vallieres sold the syrup for only C$10 million, he told the Quebec Superior Court during his trial.

Canada is the largest exporter of maple products, and Quebec holds the world's only strategic reserve of the sweet topping.

Last year, maple syrup producers started releasing more than half of the reserve to ease a syrup squeeze as the pandemic boosted demand as more people started eating at home.