LONDON (AFP) - British boy Ashya King is due to receive treatment for his brain tumour in the Czech Republic, his family said on Wednesday, after getting the green light from the British hospital responsible for his care.

Police in Spain on Tuesday released the parents of the five-year-old after they were detained there under a European arrest warrant for taking their child out of the University Hospital Southampton without the consent of doctors due to concerns over the treatment he was receiving. They rushed to the boy's bedside in southern Spain on Wednesday after walking free from jail.

Mr Daniel King told the BBC he had seen his brother, who is now being treated at a hospital in Malaga, southern Spain, on Tuesday, and said that he was physically "fine" but "emotionally very confused". He also confirmed that Ashya was set to travel to the Proton Therapy Centre (PTC) in Prague to receive specialist treatment unavailable in Britain. "The reason we chose Prague is because it's the best solution in Europe and also cheaper than going to America," he explained.

Grandmother Patricia King added that Ashya would not be able to cope with the pressure on board a long-haul flight.

Mr Brett King, 51, took his son out of the southern England hospital last week after he claimed doctors had blocked his attempts to take Ashya abroad for proton beam therapy.

He also claimed that doctors had threatened to ask for a protection order and take the child away if he interfered with his treatment plan.

"We are on our way to help my son," Mr King said in his first public declaration since British prosecutors dropped extradition proceedings against him and his wife for taking Ashya without doctors' consent.

"We just want to show love to him because without that there is no purpose to life," a visibly shaken Mr King told reporters after he and Ashya's mother Naghemeh, 45, were freed in Madrid late on Tuesday.

"When we were in prison there was no minute that went by without our hearts hurting to see Ashya," Mr King told a news conference in the southern city of Seville.

"My wife spent most of the time crying in the cell."

"He hasn't got too many months to live and we're locked away in a cell," the 51-year-old father told reporters. "We are just trying to speed things up to help him."

Mr King said on Wednesday he believed the radiotherapy treatment planned by doctors in England would have turned Ashya into a "vegetable".

"It is not the answer for a child of five. It is too strong for a child," he said.

The Kings want Ashya to undergo an alternative treatment called proton beam therapy. Mr King said the family is selling its apartment in Malaga to fund the therapy.

"My son is worth everything, worth me going to prison. Everything," he said.

Ashya's parents headed afterwards for the coastal city of Malaga, where he is being treated in a children's hospital, to see him for the first time since their arrest on Saturday.

The Prague centre said on Wednesday that Dr Gary Nicolin, a consultant paediatric oncologist at the British hospital, had sent to them Ashya's complete medical reports.

It said proton therapy would be a suitable method of treatment for Ashya, but that he

would need to go back to England first to undergo two cycles of chemotherapy.

"Ashya shall go for proton therapy to the Czech Republic," said Dr Jiri Kubes, head of proton therapy at the centre.

The case prompted an outcry in Britain, where some 130,000 people signed a petition calling for the boy to be reunited with his parents.

Grandmother Patricia King argued that the warrant should never have been issued and accused Hampshire Constabulary and Southampton General Hospital of dealing in "lies and then U-turns".

British Prime Minister David Cameron welcomed news that the case had been dropped, saying on his Twitter feed: "It's important this little boy gets treatment & the love of his family."

Deputy Prime Minister Nick Clegg said it was "not appropriate" to "throw the full force of the law" at Ashya's parents.

The chief of police in Hampshire, the force which originally applied for the arrest warrant, acknowledged on Tuesday that "the situation today is not right".

"Ashya needs both medical treatment and for his parents to be at his side," said Mr Simon Hayes, Hampshire's police commissioner, in a statement.

Mr King criticised doctors at the hospital in a video posted on YouTube before he was detained. He appeared in the footage holding Ashya, who was fitted with a feeding tube.