The hospital caring for sick toddler Alfie Evans has said it will seek legal advice over a date when his life support can be withdrawn.
The boy's parents, who want to send the 22-month-old abroad for treatment, lost a final legal appeal in March.
Recent reports suggested the family had been given fresh hope that Alfie could be capable of travelling.
However, Alder Hey Hospital said it would now ask the High Court for "guidance" about when to withdraw care.
In a Facebook post, Alfie's mother Kate James accused the hospital of "going behind our backs" and giving them "false hope".
Alfie's parents had taken their fight to keep him alive to the Supreme Court last month, but judges upheld an original High Court ruling that he should only receive palliative care.
Earlier this week The Pope tweeted in support of Alfie's family and North West England MEP Steven Woolfe also offered his support.
On Thursday, Mr Woolfe said he had attended a meeting with officials at the Liverpool hospital, where Alfie's father Tom Evans presented what he believed was fresh evidence.
His understanding was that a decision on ending life support was on hold for the hospital to review the case and consider "alternative options", including taking Alfie to Italy for treatment.
But a fresh statement from Alder Hey said it would now return to the courts after failing to reach an agreement with his parents.
The statement said: "We always aim to reach agreement with parents about the most appropriate palliative care plan for their child but sadly, in this case, we have not been able to do this.
"Consequently we must return to the High Court, as we are legally required to do, for guidance about a date on which to withdraw treatment from Alfie."
The hospital also called for its staff to be "treated with respect" following and "unprecedented amount of queries" from the public.
The BBC understands several online messages and emails sent to the hospital have been abusive.
Alfie has a rare degenerative neurological condition that has not been definitively diagnosed by doctors and remains in a "semi-vegetative state"
Ms James' Facebook post said: "We were not notified in the meeting that they were taking this back to [the High Court].
"We are disgusted in what they have done and how they can get away with this."