The battery on the feeding system of missing five-year-old boy Ashya King is "now likely to have expired", police have said.
Ashya's family took him from Southampton General Hospital at around 2pm yesterday, before travelling on a ferry to France around two hours later.
Hampshire Police Asst Ch Cons Chris Shead said medical experts had told them in the last hour that the battery life on the machine which feeds him would have died by now.
We don't know whether the King family have any spares, the knowledge, or any way of recharging the battery. If they don't, without properly administered food, Ashya's condition will deteriorate very quickly. With each hour that passes our concern for him grows.
Ashya King's parents told the Daily Mail they fled the UK after being told NHS treatments would leave him with life-long disabilities.
The head of the police force which applied for a European Arrest warrant against the parents of Ashya King has now urged their release.
A British mother whose son's life was saved by proton therapy has told ITV that she defied NHS doctors' advice to pursue the treatment.