The parents of Ashya King will remain in police custody and unable to visit their five-year-old son in hospital after their extradition hearing in Madrid was adjourned for three days.
Brett King, 51, and his wife Naghmeh, 45, from Portsmouth, told the court they did not want to be extradited back to the UK, according to Sky sources.
Ashya, who has a brain tumour, is also not able to have visits from his six siblings who are also still in Spain because he is under police guard at the Materno-Infantil hospital in Malaga.
The boy's parents were arrested on Saturday after taking Ashya out of Southampton General Hospital to seek specialist cancer treatment abroad.
The five-year-old is unable to see members of his family
Petitions on change.org calling for the release of the Kings so they can get medical treatment for Ashya have now gathered nearly 20,000 signatures.
It comes after Portsmouth City Council revealed on Monday that the little boy was made a temporary ward of court on Friday.
Julian Wooster, the council's director for children's services, said: "At the request of Southampton hospital the council obtained a temporary Wardship Order on Friday, only to direct that Ashya King be presented for medical treatment.
"The order will be reviewed by the High Court on Wednesday. We understand this is an extremely difficult time for Ashya and his family."
Ashya King, pictured with father Brett, needs treatment for a brain tumour
Ashya's grandmother Patricia King said authorities were treating Brett and his wife "like murderers".
She said: "They've treated them like murderers, putting handcuffs on them and everything. There's no human rights for our family at all, it's disgusting.
"He's there in the hospital, he doesn't know anybody, there's police guarding him, he can't speak, he doesn't understand Spanish.
The hearing took place in Madrid - 300 miles from Ashya's hospital
"My daughter-in-law and my son have begged to see him, but they've been refused."
His brother, Naveed, 20, posted a video blog claiming the family had stocked up on food and syringes that the boy needed ahead of their journey and had bought him a new wheelchair costing up to £1,600.
Patricia King earlier said her son was selling his holiday home in Spain to pay for proton beam therapy, which costs an average of £100,000 per person.
British police officers are understood to have arrived in Spain to question Ashya's parents.
The family travelled to southern Spain through Cherbourg in France
Dr Jiri Kubes, a proton therapist in the Czech Republic where the family was hoping to get treatment for Ashya, said cancer clinics could treat him "within a few days" if a request was received from his doctors.
Janice Atkinson, UKIP South East MEP, said: "This little boy needs his mother at this time. He is five years old, probably doesn't speak Spanish, and will be lying in a hospital bed in distress.
"I call on the Home Secretary to contact the Spanish authorities so that Ashya's parents are released immediately. Then she should ask the assistant chief constable of Hampshire why he 'made no apology for the police being proactive' to find Ashya."
A spokesman for David Cameron said: "I think people up and down the country will understand and be moved by the grave illness from which Ashya is suffering.
"First and foremost, the priority must be that he receives the very best and most appropriate medical care.
"Of course, I am sure that every parent wants to do the best for their child. That is probably the most human of human instincts."