Little Younes went missing on the night of October 25 when he left the family home barefoot and lightly dressed, after an argument between his parents, according to the initial investigation by prosecutors.

The body of the Belgian boy was found in the Lys river at the Belgian-French border, near a lock at Comines, which is about 12 kilometres (7.5 miles) from where the boy had disappeared, Maertens said.

The prosecutor also said the body had not been weighed down in the water, contrary to some earlier media reports.

The police chief in Comines, Sebastien Dauchy, said that investigators had previously searched the Lys river at the same spot but had found nothing.

"It was a boatman who saw a body mass in the water," Maertens said.

"He was wearing a sweater, underpants and trousers which matched the description given by the parents," she said.

Maertens said that confirming that it is Younes's body was essential in order to "relaunch the investigation" into his disappearance.