Media playback is unsupported on your device Media caption A video clip posted on YouTube before the couple were arrested showed Mr King explaining why they had travelled to Spain

Police say they will not apologise for the way they conducted a search for a five-year-old boy with a brain tumour, who was removed from a UK hospital by his parents against medical advice.

Ashya King was found in Malaga, Spain on Saturday following an international search. His parents have been arrested.

In a video posted on YouTube, Ashya's father, Brett King, said there had been a "ridiculous chase".

Hampshire Police said medical advice was that Ashya was in "grave danger".

Southampton General Hospital said the family had been offered a second opinion over Ashya's condition.

Media playback is unsupported on your device Media caption Assistant Chief Constable Chris Shead: "We had to act on warnings"

Assistant Chief Constable of Hampshire Police Chris Shead said: "I make no apology for being as proactive as possible in trying to find him.

"I'd much rather be standing here facing criticism over being proactive than do nothing and explain why a child has lost his life."

Following the discovery of the family, Ashya was taken to hospital in Malaga. He has since been moved from a high dependency to a lower dependency unit.

Media playback is unsupported on your device Media caption Brett and Naghemeh King attended a court in Malaga on Sunday night

Mr King and his wife Naghemeh have not been charged with any offence in Spain.

The couple are expected to appear in court in Madrid on Monday where a judge will consider grounds for their extradition to the UK.

On Sunday evening, they were driven by police to a court in Velez Malaga, 30 miles east of Malaga city.

They were believed to be speaking to a judge who would decide whether they would travel to Madrid that evening.

As they left, Mr King told the BBC: "We just want the best for Ashya."

'Very angry'

Speaking after Mr Shead's comments, Ashya's paternal grandmother, Patricia King, told the BBC she thought the five-year-old would be better off staying in Spain.

Media playback is unsupported on your device Media caption Ashya's grandmother describes her anger over the events surrounding her grandson

She said she was "very, very angry" at the way the investigation had been handled, saying: "It has been taken too far - much too far," with Ashya now separated from his parents following their arrest.

Ms King, who lives in Southsea, said the experience had been "terrible" for Ashya's parents.

In the Youtube video, Mr King said he and his wife were seeking a treatment for Ashya that he had not been offered.

He said they wanted Ashya to have proton beam radiotherapy - a treatment that targets tumours directly - because they did not want him to be "pelted with radiation".

Image copyright Hampshire Police Image caption Ashya is being treated in a Spanish hospital

Mr King said the couple had "pleaded" with Southampton General Hospital for Ashya to receive the treatment, but were told it would have "no benefit whatsoever".

Responding to the claims made in the video, a spokesman for the hospital said: "Our priority has always been Ashya's welfare and we are delighted that he has been found.

"Throughout Ashya's admission we have had conversations about the treatment options available to him and we had offered the family access to a second opinion, as well as assistance with organising treatment abroad."

The charity Cancer Research UK says proton beam treatment is available on the NHS in the UK only for eye conditions.

However, in some circumstances the NHS will pay for patients to go abroad for proton treatment.

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

Sources: NHS England, Cancer Research UK

Police officers from Hampshire have travelled to Spain to "assist the Spanish officers in the extradition proceedings", Mr Shead said.

The Foreign Office is assisting the family, he added.

The couple had travelled to Spain, where they own a property, in order to raise money for Ashya's treatment elsewhere.

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