Ashya King's brother Naveed has spoken of his heartbreak at not being able to see his sick brother who is in a Spanish hospital while their parents fight extradition to the UK.
Ashya, five, has a brain tumour and needs constant medical help.
His parents Brett, 51, and Naghmeh, 45,took him from Southampton General Hospital last Thursday and travelled on a ferry to France with the boy and his six siblings before heading south to the Costa del Sol in southern Spain.
They spent last night (Monday, September 1) separated from their son after a judge ruled the couple must be held for up to 72 hours while the court considers whether to grant a British extradition request.
Hampshire Constabulary had obtained a European arrest warrant on the grounds the Kings neglected their son.
The ordeal is taking its toll not just on Ashya and his parents, but also his siblings, said older brother Naveed.
In an interview with Jon Snow, he told Channel 4 News: "We're not allowed to go and see Ashya at all. There is police standing outside his hospital room."
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The family are staying in a hostel but are being starved of information about what is happening to their brother and mum and dad.
Naveed said: "Including taking care of all the kids, we're having to do the research ourselves to find out information.
"We're not getting anyone knocking on our door to tell us everything is okay. We've got lots of support from friends and family out here.
"My mum was by his [Ashya's] side for the whole month that he was in hospital so for him to now suddenly not be with anyone of the family, and because he can't really move much of his body we kept him entertained, we played games with him, we make sure that he was always happy.
"His health might actually deteriorate because he can't be entertained and be happy."
Naveed said that friends of the family had set up a petition and fund-raising campaign to help Ashya's parents get the proton beam treatment they see fit for him in the Czech Republic.
The treatment is not available on the NHS.
He said: "We wanted the best for Ashya and for us to know that now they've taken him away from us and maybe given him treatment that may not be best for him, it's quite heart-breaking. Especially now that my other brothers can't see my parents, that's heart-breaking for them."
A ruling on whether the Kings will be transferred to a Madrid court for an extradition hearing is expected today.
Meanwhile, back in Britain, the Crown Prosecution Service announced the case had been put under 'immediate review'.
The CPS said in a statement: "Further evidence is now being provided to the CPS and so the case is under immediate review."
And Deputy Prime Minister Nick Clegg backed calls for them to be reunited.
He said it was 'not appropriate' to 'throw the full force of the law' at the parents.
He said: "A little boy is on his own in a hospital, doesn't speak Spanish, is cut off from his parents and his siblings and I would like to see him together with his family as soon as possible.
"As far as I can make out, this is a family in a state of real anguish who have taken this exceptional step of moving their sick child to another country because they think that's what is best for their child."
You can watch Nick Clegg's interview below: