Family want inquiry into baby death.
Ten-month-old Luke Winston-Jones, from Holyhead in North Wales, died at Alder Hey Children's Hospital in Liverpool in the early hours of yesterday.
He was given only days to live after he was diagnosed with the genetic disorder Edwards syndrome shortly after birth.
Last month, doctors caring for Luke were granted permission by the High Court to withhold life-saving treatment by 'aggressive' mechanical ventilation if his condition deteriorated.
His aunt, Jacqui Kirkwood, who was with Luke when he died, claimed doctors did not give him the treatment which the court had ordered was acceptable.
A spokeswoman for Alder Hey Children's Hospital denied the allegation and said medical staff had 'fully complied' with the High Court ruling.
Mrs Kirkwood said doctors refused to carry out procedures which the family believed would have prolonged Luke's life.
She added: 'We want a full inquiry into what happened, we will not let this rest.'
The hospital spokeswoman said: 'Senior clinicians at the Trust were present at the time and attempted to resuscitate Luke.
'Luke's condition had significantly deteriorated over the past 48 hours and so, despite extensive resuscitation lasting over an hour, we were unsuccessful.
'The Trust is confident that it has always acted in the best interests of Luke and have fully complied with the recent ruling from the High Court.
Luke's mother, Ruth, said she was 'severely traumatised' by the events.
She said: 'It is the end of my world, I have lost my precious little boy.'
Luke had never left hospital during his short life.
His mother had set up an appeal fund to pay for his care, which was supported by the Duchess of York.
Ruth Winston-Jones with her son Luke