A senior hospital official has admitted there was "grave negligence"
A baby born prematurely to the first woman in Spain to die of swine flu has also died after a glaring medical error, a hospital director has said.
The baby boy was born by Caesarean section on 29 June just hours before his mother, Dalila Mimouni, died.
Doctors said the baby, Rayan, did not have swine flu and he seemed to be doing well despite being premature.
But he has now died after an elementary feeding error by a member of staff, said the hospital's managing director.
Antonio Barba told a news conference that on Sunday night the child was fed intravenously instead of through a gastric tube.
The mistake was detected about an hour later, and doctors battled through the night to try to save the child by cleaning his blood.
But Rayan died just after midday on Monday, said Mr Barba, managing director of the Gregorio Maranon hospital in Madrid.
Mr Barba said the error was "very grave negligence and there is no excuse for it.
"The hospital assumes all responsibility, both human and financial, although we know there is no making up for something like this," he said.
Mr Barba said the nurse who made the error was working on the unit for the first time and her supervisor was temporarily absent.
Dalila Mimouni, Rayan's 20-year-old Moroccan mother, died of respiratory illness caused by swine flu on 30 June.
She died just hours after Rayan was delivered by emergency Caesarean section two months before his due date.
The case had gripped the Spanish media.
Mimouni's bereaved husband had already announced his intention to take legal action against two hospitals, including Gregorio Maranon, after his wife's complaints of feeling unwell were repeatedly dismissed before she was finally diagnosed, reports El Pais newspaper.