The couple in their 40s had been on the famous Chia beach on the island.
They were preparing to travel home on a ferry at the Sardinian port of Porto Torres, towards Toulon (Var, Provence-Alpes-Côte d'Azur), when they were stopped during a routine check at Italian customs, for illegally carrying 14 plastic drinking bottles - weighing 40kg - full of beach sand.
The couple now faces up to six years in prison for aggravated theft of public property.
They maintain that they wanted the sand as a simple “souvenir” and did not realise that their actions were illegal. The bottles had been left easily visible in the car, reports said.
Porto Torres, 40 chili di sabbia nascosti nel suv. Nei guai una coppia di turisti francesi https://t.co/Rx3tEy4tX3 pic.twitter.com/qtkdtLy2rG— La Nuova Sardegna (@lanuovasardegna) August 16, 2019
The coveted sand in Sardinia - which often appears soft white or pinkish in hue - is considered public property. It is forbidden to remove it from the beach. It is also illegal to pick up and keep beach pebbles and shells, with fines for doing so going up to €3,000.
In 1994, Sardinia banned access to the famous pink beach on Budelli Island, amid fears that its sand was disappearing due to tourists taking it home. There are concerns that several tonnes of sand disappear from the island every year, with the potential to destroy the beaches long term.
There is also said to be an illegal trade in Sardinian sand on online auction sites.
The couple is not the first high-profile sand case in recent years; last year, an Italian man living in the UK was fined €1,000 after he was found to have a bottle of sand from Sardinia’s Gallura beach.
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