Ashya King: Father's joy at Malaga hospital reunion
Ashya King's father has spoken of the family's joy as they were reunited with the five-year-old at the Spanish hospital where he is being treated.
Brett and Naghemeh King were held in a Madrid prison after taking their son, who has a brain tumour, from a hospital in Southampton against medical advice.
The couple were released on Tuesday after UK prosecutors withdrew a European arrest warrant.
Mr King said Ashya was "so happy" and "so pleased to see us".
Leaving through a back door of the Materno-Infantil hospital with his older son Danny, Mr King said: "He couldn't breathe he was so happy.
"He was so pleased to see us. We're trying to be hopeful."
He added: "Tomorrow I meet with the cancer specialist. We'll do what it takes. Not much else to do."
Mrs King is expected to stay at the hospital with Ashya overnight. His condition is described as stable.
A hospital spokeswoman said local authorities had received notification from British officials that the parents should not be allowed to take Ashya as he is still a ward of court in the UK.
Police in Hampshire sparked an international hunt for the Kings after they took Ashya from Southampton General Hospital without doctors' consent to seek proton beam treatment abroad.
The force obtained a European arrest warrant on the grounds the Kings had neglected their son, and the parents were arrested in Spain on Saturday.
Following the couple's release from Madrid's Soto Del Real jail, Mr King said: "They arrested us and directly they took my son away and said he was not allowed to have any visitors.
"We want to help our son get through this bad time because he hasn't got too many months to live and we're locked away in a cell - we're just trying to speed things up to help him."
In an exclusive interview, Mrs King told the BBC's Jon Kay: "All I could do was just cry and pray.
"What could I do in a prison cell? I could not do much, really.
"I just want to wet [Ashya's] mouth because he can't drink through his mouth, I want to brush his teeth, I want to turn him side to side every 15 minutes because he can't move.
"I just want to do all those things I was doing from Southampton, I want to do it for him here."
Asked how angry the couple were, Mr King said: "My heart is aching for my son and anger can't come in at the moment because I've just got these feelings that I've got to see my son's face."
Ashya was diagnosed with a medulloblastoma, a type of brain tumour, which was removed by surgeons last month.
His parents want him to receive proton beam therapy to prevent the tumour returning. They have been told Ashya can receive treatment at the Proton Therapy Center in Prague.
Mr King said he took Ashya without notifying the hospital in Southampton because he believed doctors would block the treatment.
The child was made a ward of court last week, at the request of Portsmouth City Council.
The Judicial Office said no decision about Ashya's future can be taken without the court's approval and a hearing has been scheduled for Monday.
A spokesman said the Kings would have "an opportunity to be represented and put forward their proposals for Ashya's treatment" at that hearing.
Children's cancer charity Kids'n'CancerUK, based in Derbyshire, said it has been inundated with donations to help fund Ashya's treatment and associated costs estimated at £150,000.
Chief executive Mike Hyman said: "We've had £35,000 in 24 hours and it shows no sign of stopping.
"We have had elderly people call up and donate their pensions - you cannot buy that sort of generosity."
What is proton beam therapy?
It uses charged particles instead of X-rays to deliver radiotherapy for cancer patients
The treatment allows high energy protons to be targeted directly at a tumour, reducing the dose to surrounding tissues and organs
In general, it gives fewer side-effects compared to high energy X-ray treatments
It can be used to treat spinal cord tumours, sarcomas near the spine or brain, prostate cancer, lung cancer, liver cancer and some children's cancers
In December 2011, the UK Department of Health said that proton therapy will be made available for patients in London and Manchester from 2018
Speaking about the family's relationship with doctors in Southampton, Mr King said: "They threatened me previously. When I asked about his cancer... they said if I ask anymore questions the right for me to make a decision will be taken away from me because they get immediate courts paper to say that they have right over my child.
"I had so much fear to mention anything to them because they could have stopped my son getting any treatment and just forcing this very strong treatment on him.
"So from that moment on I had to keep everything quiet."
Dr Pete Wilson, chief paediatrician at Southampton General Hospital, said doctors had told the family they believed proton beam therapy had "no benefit" but had still agreed to refer him for the treatment to be paid by the family and were in the process of helping them down this route.
He also denied any threats were made, adding: "When they [doctors] were asked directly by the family what would happen if they refused treatment, any treatment, they were told that in exceptional circumstances, as doctors, we would need to act in Ashya's best interests and that may need going to the court.
"We are very clear that the message that we were giving them was consistent and that we got it across. I think there are cases where the family just disagrees with us."
Health Secretary Jeremy Hunt has said a cancer specialist will be flown out to Spain to give Ashya's parents advice on the best course of action.
During Prime Minister's Questions, David Cameron agreed to look "very carefully" into an independent child guardian scheme.
Belfast South MP Alasdair McDonnell proposed that guardians be given the power to reflect the best interests of the child to all the relevant authorities and services.