The family of Charlie Davis have claimed the youngster was playing near his home in Hull when he was snatched by a local youth, pulled 200 yards along a path and tied to a tree by a railway line before being battered.
But officers say they have no evidence at this stage to confirm reports that he was abducted or tied up on wasteland at Hessle, Hull, near the Humber Bridge.
The youngster remains in Hull Royal Infirmary where a scan has revealed no damage to his brain - his mother Susan is by his bedside.
The family called the police after the boy was found at lunchtime on Thursday by a couple.
However, a Humberside Police spokeswoman said: "Clearly this little boy has had a nasty attack. He's been hit by a brick and he's got some horrible injuries.
"But at this stage there's no information that we have pointing to the fact that he's been abducted and, again, being tied to a tree is something that hasn't yet been clarified.
"We haven't spoken to the four-year-old and therefore we haven't got an account of what happened."