A frantic police hunt is underway for a five-year-old boy with a brain tumour taken from a British hospital by his family, as fears for his life intensified with every passing hour.

Ashya King’s parents took him on Thursday from a hospital in the British south coast city of Southampton without doctors’ consent and boarded a ferry to the French port of Cherbourg.

It is not known why Brett King, 51, and Naghemeh King, 45, took their son. While they are Jehovah’s Witnesses, the movement said Friday there was no indication their decision was motivated by religious convictions.

“There are serious concerns for Ashya’s health, he is immobile and likely to be in a wheelchair or buggy, and cannot communicate verbally,” Interpol said.

The missing persons alert went out to all 190 Interpol member countries, dramatically stepping up the hunt for the missing child.

Detective superintendent Dick Pearson from police in Hampshire, southern England, who is leading the investigation, said: “If we do not locate Ashya today there are serious concerns for his life.”

The youngster, who has undergone extensive surgery and was last operated on seven days ago, is fed through a tube on a battery-operated system.

Hampshire Police assistant chief constable Chris Shead said late on Friday: “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.

“With each hour that passes our concern for him grows.”

In a statement, the hospital in Southampton said Ashya was allowed to leave the ward under his parents’ supervision and hospital staff raised the alarm when the length of his absence “became a cause of concern”.

“The information we have received from his medical team at Southampton General Hospital is that he must continue to be fed via a tube by someone with the relevant medical training,” Shead said.

“If he doesn’t receive urgent medical care, or the wrong treatment is given, his condition will become life-threatening.”

Cherbourg prosecutor Eric Bouillard said authorities considered the boy had been “kidnapped given the circumstances of his departure from hospital”.

“For the moment, what we most want to do is contact the family,” he added.

Jehovah’s Witnesses are known for refusing blood transfusions on religious grounds, but they are otherwise open to other medical procedures.

The religious movement confirmed on Friday that the parents are members.

“However, we are not aware of the facts of the case nor the reasons for the family’s medical choices which are personal decisions,” it said in a statement.

French authorities say the family arrived on Thursday night with their seven children and were driving a grey Hyundai with the number plate KP60 HWK.

The other six children are between three and 22 years old.