POLICE say concerns for Ashya are growing with each hour.
Hampshire Constabulary have also confirmed that medical experts have said the battery life on the machine administering his food is likely to have expired now.
Officers also said they have had one reported sighting of the King family, on the ferry to Cherbourg yesterday.
Assistant Chief Constable Chris Shead said: "Ashya is still missing, and with each hour that passes our concern for him grows.
"Within the last hour, we have been told by medical experts that the battery life on the machine that administers his food is now likely to have expired. 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.”
Chief Const Shead continued: "Our message remains the same: please help us find him. Please visit the Hampshire Police website or Hampshire Constabulary Facebook page and share the appeal and the photos of Ashya, his mum and dad Brett and Naghmeh, and the car that they were travelling in when they left for Cherbourg.
"We have had a good response to widespread media coverage, with people who know the King family calling in.
"So far, we have had one reported sighting of the family, which was on the ferry to France yesterday.
"There have been widespread media alerts across Europe, focussing on countries where the Kings had a known association; and in particular, we continue to work closely with French authorities.
"The last positive information we had placed them in France, but by now, we cannot be certain they have not moved on. Our enquiries are totally focussed on establishing where they are now. There is still time to find Ashya and make sure he gets the medical help he urgently needs, but we need the public’s help to do this.
"The registration of the grey people carrier that the King family are travelling in is KP60 HWK.
"If you see it, if you think you may have seen Brett, Naghmeh, Ashya and the six other children, please call us now on +441962 841534 or dial the European emergency number on 112 as soon as possible."