Bones, including a skull, were discovered by a walker near Le Vernet in the Alpes-de-Haute-Provence on Saturday.

Forensic tests showed they belonged to the boy, known only as Emile, French broadcaster BFMTV said, quoting prosecutors.

Some reports named him as Émile Soleil.

Prosecutor Jean-Luc Blachon said: "On Saturday, the police were told of the discovery of bones near the hamlet of Le Vernet."

After testing them, police concluded on Sunday that "they were the bones of the child Emile," he added.

Mr Blachon, who was quoted by France24, did not give a cause of death, but said that forensic investigators were continuing to analyse the remains, while police carried out further searches.

The boy was last seen by two witnesses walking down a street near his grandparents' house on 8 July last year, according to authorities at the time.

He had arrived in the area the day before to stay with his maternal grandparents for the summer holidays.

Francois Balique, the local mayor, said at the time that the couple "realised he was no longer there when they went to put him in the car".

They live in a remote mountain village with only two dozen inhabitants just outside Le Vernet, between Grenoble and Nice.

The little boy was less than 3ft tall and was wearing a yellow T-shirt and white shorts when he was last seen.

A massive ground search involving dozens of police officers and soldiers, supported by sniffer dogs, a helicopter and drones, failed to find him, as did a reconstruction in which his family took part.

Police admitted they had no idea what had happened to him.

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A prosecutor said after several days it was unlikely such a young child would have survived in the summer heat.

The case, which began as a missing person investigation, soon became a criminal inquiry into a possible abduction, although police did not rule out murder, an accident or a fall.

In late November, a day before Emile would have turned three, his parents published a call for answers in a Christian weekly publication, France 24 said.

"Tell us where he is," they wrote.