William Callaghan survived three days lost in bushland Image copyright EPA

William Callaghan, a 14-year-old with non-verbal autism, became lost during a family walk at Mount Disappointment, in Victoria, on Monday.

His family had raised concerns that his inability to verbally communicate may hinder search efforts.

He was found on Wednesday near the peak of the mountain.

Rescuers said William had been located about 10 minutes off a bush track - he did not have his shoes but was wearing tracksuit bottoms and a hooded sweatshirt. 

It was not yet known if William had access to food, water or shelter on the mountain, located 80km (50 miles) north of Melbourne. Temperatures had neared 0C in the past two nights.

He appeared to be "remarkably well for the time that he's been out there", said Insp Christine Lalor of Victoria Police.

She told reporters he had been taken to hospital for monitoring, adding: "He's alert, warm, eating and drinking and he actually asked for McDonald's."

William's mother, Penny Callaghan, thanked volunteer rescuers and police.

"I can't imagine what he's been feeling and going through and I'm just so grateful and so relieved," she told reporters.

Police had asked locals to lay out feta cheese, peanut butter and other condiments in a bid to attract his attention. They were also encouraged to play the Thomas the Tank Engine theme.

An autism advocacy organisation praised authorities for adapting their search.

"We really need to adapt ourselves to the needs of autistic people rather than expecting them to behave as we do, or as neuro-typical people do," Amaze chief executive Fiona Sharkey told the ABC. BBC