THE lawyer for the family of brain cancer patient Ashya King says they will sue Southampton General Hospital.
Juan Isidro Fernandez Diaz, who is representing Brett and Naghmeh King, claimed the family will take legal action against doctors.
He said: “They will be taking legal action against the doctors who libelled him in the hospital and they will file a criminal complaint for false detention and libel.”
Mr Diaz said the couple ''wanted the very best for their child''.
He said: ''They never thought that they committed any crime in the UK.
''The child is in perfect condition. All the doctors said (there was) no problem with the child to travel from England to Spain because the father knows (how) to give treatment to the child
''We are saying the boy is not in danger. The big brother is with the boy and he is in perfect conditions.''
It comes as the parents of five-year-old Ashya spent another night away from their son as relatives and supporters continued to demand their release from detention.
A judge in Spain ruled that Mr and Mrs King must be held for up to 72 hours while the court considers whether to grant a British extradition request.
The couple, who were arrested in Spain after Ashya was taken from a UK hospital without doctors' consent, told the judge in Madrid they do not want to return to the UK.
The boy is being treated in a hospital in Malaga and his grandmother and brother have criticised the way his parents are being treated although it is understood that his eldest brother Danny was allowed to see Ashya yesterday.
The family took him from Southampton General Hospital last Thursday and travelled to France with him and his six siblings before heading to the Costa del Sol in southern Spain.
Mr King, 51, and Mrs King, 45, were arrested on Saturday night in Velez-Malaga.
The couple travelled to Spain to sell a holiday home to obtain funds for proton beam therapy, which is not available through the NHS, according to reports.
Their son, who is suffering from a stage four brain tumour, is being cared for at the Materno-Infantil hospital in Malaga.
More than 75,000 people have signed an online petition demanding Ashya is reunited with his parents.
British police have defended their decision to request a European arrest warrant.
Assistant Chief Constable Chris Shead, of Hampshire Constabulary, said he was aware the police's approach had created a ''significant amount of debate'' but he would rather be criticised for ''being proactive'' than ''potentially having to explain why a child has lost his life''.
Simon Hayes, police and crime commissioner for Hampshire and the Isle of Wight, said: ''Hampshire Constabulary's role, as in many other cases, was to safeguard the interests of a very vulnerable sick young child and find Ashya.''
The Crown Prosecution Service said the case was under ''immediate review'' and a decision will be made whether to prosecute.
A spokesman said it had applied for the arrest warrant ''at the request of Hampshire Police for an offence of cruelty to a person under the age of 16 years'' on Friday.
The CPS reviewed the evidence available at that time. ''Further evidence is now being provided to the CPS and so the case is under immediate review.''
The Proton Therapy Centre in Prague confirmed it was able to treat Ashya immediately if he was eligible for therapy, with the cost of the treatment to be sorted out later.
Director of strategy Iva Tatounova said Naveed had been in touch with the centre yesterday, giving details of the Spanish doctors treating Ashya, and saying they were willing to send the centre the result of his MRI scan.
''We have asked them to do that, so we can assess the boy's condition,'' she said.
''There would have to be a recommendation from the doctors in Southampton, but we are here, and willing to co-operate.''
Dr Michael Marsh (above), medical director at University Hospital Southampton NHS Foundation Trust, said he regretted the relationship with the Kings had broken down.
He added: ''We have discussed proton beam radiotherapy with Ashya's family and there are some tumours that respond well to this type of treatment, but there are some cases where there isn't the evidence that this is a beneficial treatment. Where the evidence supports this treatment, we have made a referral and patients have been treated abroad.''