The boy suffered a serious head injury after the bin was thrown down on the tent from a height of 20 metres. The incident happened at Bergeggi, near Savona, in the northern province of Liguria.
He was taken to the intensive care unit of the Gaslini paediatric hospital at Genoa, which issued a statement saying it was too early to say how bad his injuries were.
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“It's a criminal act,” the boy's father told the local daily, Il Seccolo XIX. “We hope that those responsible will be found.” He and his wife were appealing to anyone who saw what happened to go to the police, he added.
The parents and their two other children, aged 14 and 15, were all sleeping on the beach at the time of the incident.
Local police were working on the basis that this was a deliberate act, the website of the daily newspaper Corriere della Sera reported.
They had not ruled out the possibility that this was a response to illegal camping, it said, adding that a second bin had also been thrown.