Police have said emergency services were called at about 3am “after concerns were raised for a man seen near a vehicle”.
Upon arriving at the scene police spoke to Thorpe, who was sitting in a vehicle in the street, and he was then taken to hospital for assessment.
“No official complaint has been made and no further police action is anticipated,” police said.
Thorpe’s manager James Erskine said the swimmer’s “dazed and confused” state was the result of a combination of antidepressants and painkiller he has been taking for a shoulder injury.
“There was no alcohol involved, he hadn’t been drinking or anything like that,” Erskine said. “He became disorientated and he tried to get into what he thought was a friend’s car, but it wasn’t his friend’s car at all.
“It looked the same and I think it was the same make, same colour, and obviously somebody saw it or the owner of the car saw it [and] called the police.
“The police came; they were fantastic, they realised it was Ian Thorpe and they called an ambulance.
“The hospital then suggested – or more than suggested, I think – that he should go into rehab for depression and that’s what’s happened.”
Thorpe, who has been living in Switzerland for the past 18 months, had been staying with at his parents’ home in Panania over Christmas.
This comes after Thorpe left hospital care early on Friday, having been under medical supervision since Wednesday night for depression and alcohol abuse.
Thorpe’s manager James Erskine refuted claims that he had spent time in alcohol rehabilitation and claimed he was in hospital for a shoulder operation.