Alex Batty has returned to the UK six years after disappearing on holiday in Spain with his mother and grandfather, the PA news agency understands.
The 17-year-old, who was aged 11 when he went missing, has returned from France as detectives prepare to hold a press conference at Greater Manchester Police’s headquarters.
He was found by chiropody student Fabien Accidini while walking alone near Toulouse in the early hours of Wednesday.
His grandmother and legal guardian Susan Caruana previously said she “can’t wait” to see him when he returns.
Ms Caruana, from Oldham, Greater Manchester, added on Friday: “I cannot begin to express my relief and happiness that Alex has been found safe and well.
“I spoke with him last night and it was so good to hear his voice and see his face again. I can’t wait to see him when we’re reunited.
“The main thing is that he’s safe, after what would be an overwhelming experience for anyone, not least a child.
“I would ask that our family are given privacy as we welcome Alex back, so we can make this process as comforting as possible.”
It is thought Alex had been living an “alternative” lifestyle with his mother and grandfather across Spain, Morocco and France while he was missing.
Mr Accidini said the teenager told him he had been hiking in nearby mountains for more than four days in an attempt to return to England.
On Friday, French prosecutors said the teenager’s mother, Melanie Batty, who is wanted in connection with his disappearance, may be in Finland, while his grandfather David Batty has died.
Antoine Leroy told reporters Alex had said he knew his way of life with his mother “had to stop” after she announced an intention to move to Finland.
This led him to walk for “four days and four nights” across the Pyrenees, the prosecutor said.
On the whereabouts of Alex’s mother and grandfather, Mr Leroy said: “It is possible that the mother at this time has in fact gone to Finland, as she planned.
“The grandfather, who has always been with his daughter and grandson, is said to have died approximately six months ago.”
Alex was described as “tired” but “in good health” after being checked over by French officials and seemed “intelligent” even though he had not attended school for six years.
The prosecutor also said the boy did not appear to have been subjected to any physical violence.
Greater Manchester Police said Alex had been “well cared for” by the French authorities and had a video call with his grandmother on Thursday.