Dozens of people are facing fines of up to €3,000 (£2,580; $3,650) for removing beach sand and shells from the Italian island of Sardinia, local media report.
Authorities said on Saturday that 41 individuals had been reported for the theft of about 100kg (220lb) of items from beaches in separate incidents.
Sardinia's famed white sand is treasured on the island and it is strictly forbidden to remove it.
The trade in Sardinian sand, pebbles and shells was made illegal in 2017.
The fines imposed might seem heavy-handed, but for years islanders have complained about the theft of their natural assets.
Tourists, mainly Europeans and including some Italians, bottle the sand to keep as souvenirs or auction it online.
As part of an ongoing investigation, military and customs police in Sardinia have been monitoring airports and harbours, and also searching websites for illegal sales. Tourists attempting to remove bottled sand in their luggage have been caught during customs checks using X-rays.
Police said that in recent days they had discovered dozens of online adverts for the sale of items collected from the Mediterranean island's coasts illegally, some at what they described as "high prices".
The details of those accused of wrongdoing have been reported to the Forestry Corps (national state police) of Sardinia and face fines under the island's regional law.
The police said they had already collected about €13,000 in fines this year, adding that the seized items were being returned to the areas from which they were taken.
On a Facebook page set up to highlight the issue called "Sardinia robbed and plundered", users often describe the threat of such thefts as an environmental emergency.
Pierluigi Cocco, an environmental scientist and resident of the Sardinian capital Cagliari, told the BBC that the beaches were "the main reason why tourists are attracted to the island of Sardinia".
He added that the removal of sand could contribute to the reduction of beaches over the years, which would pose an environmental threat as climate change brings about a rise in sea levels.
The island's Forestry Corps has also said that taking sand could, over time, destroy Sardinia's beaches, which were created over millions of years.
In 2019, a French couple visiting Sardinia were caught with 40kg of sand in the boot of their SUV.
Police discovered the sand crammed into 14 plastic bottles taken from a beach in Chia, southern Sardinia.
The couple told police they wanted to take it home as a "souvenir" and did not realise they had committed an offence.