A severely epileptic child who had his cannabis medicine confiscated by the Home Office will remain in hospital after a string of life-threatening seizures.
Billy Caldwell, 12, was admitted to Chelsea and Westminster Hospital in London on Friday after his seizures "intensified", a family statement said.
His mother Charlotte told Sky News she was "absolutely devastated" that her son's "brutal condition" had "returned with a vengeance", adding: "He's a beautiful, sweet, innocent wee boy who doesn't deserve this callous treatment."
She has said the Home Office will be held accountable if he dies, calling its actions "beyond cruelty".
On Friday night the Home Office said it was in contact with with Billy's medical team and would "carefully consider what options are available" if they advise a particular type of treatment is urgently required.
Doctors said it was too dangerous to treat him with "rescue meds" at home and he can now be treated only with hospital-administered medicine.
Ms Caldwell had a batch of medicinal cannabis oil taken from her at Heathrow Airport on Monday after a flight from Canada.
Ms Caldwell said: "We've now reached the point where Billy is too ill to travel to get his medication, but his medication is stored minutes away from where we're now living in London.
"Despite the best and honest efforts of the NHS, frontline doctors are fighting Billy's condition with both hands tied behind their back because the only medication that will be effective is the cannabis oil (with banned component THC)."
Ms Caldwell credits the oil with keeping her sick son's seizures at bay, saying he was seizure-free for more than 300 days while on the medication.
She added doctors in Canada and Northern Ireland familiar with Billy's case said the situation was life-threatening.
The child, from Castlederg in Co Tyrone, started the treatment in 2016 in the US, where medical marijuana is legal.
He became the first person in the UK to receive a prescription after his local GP in Northern Ireland, Brendan O'Hare, began writing scripts.
However, there is no record of a health service prescription being dispensed.
Dr O'Hare was summoned to a meeting with Home Office officials recently and told to stop.
Ms Caldwell made the trip to Toronto and back with her sick son to get a six-month supply to treat up to 100 seizures a day, but said border officials seized the oil.
She said her son was too ill to travel to Canada to get his medication.
"If Billy dies, which is looking increasingly possible, then the Home Office, and (minister) Nick Hurd, will be held completely accountable," she said.
A Home Office spokesman said: "We are deeply sympathetic to the extremely difficult situation that Billy and his family are in.
"Billy is in the care of medical professionals who are best placed to assess the care and treatment that he requires.
"The Home Office is contacting Billy's medical team. If the team treating Billy advise a particular course of urgent action, the Home Office will carefully consider what options are available to help facilitate that advice."