A further 20 children aged under 10 have been diagnosed with hepatitis.
It comes amid a wave of mystery liver inflammation cases in young children, which experts believe could be linked to adenovirus.
Adenovirus causes a range of illnesses, including colds, sore throats, vomiting and fevers.
The UK has recorded 222 hepatitis cases in children aged 10 and under between the start of this year and May 25.
The sick were predominantly aged under five and showed signs of gastroenteritis, followed by the onset of jaundice.
Symptoms of gastroenteritis include diarrhoea and nausea.
No children have died in the UK during the mystery wave of hepatitis cases.
Dr Renu Bindra, senior medical advisor and incident director at the UK Health Security Agency (UKHSA), said:“Our investigations continue to suggest an association with adenovirus, and we are exploring this link, along with other possible contributing factors including prior infections such as COVID.
"We are working with other countries who are also seeing new cases to share information and learn more about these infections.
“The likelihood of children developing hepatitis remains extremely low.
"Maintaining normal hygiene measures, including making sure children regularly wash their hands properly, helps to reduce the spread of many common infections, including adenovirus.
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“We continue to remind everyone to be alert to the signs of hepatitis – particularly jaundice, look for a yellow tinge in the whites of the eyes – and contact your doctor if you are concerned.”
The UKHSA emphasised that there was no evidence linking the new cases to the Covid vaccine.
Most of the children who suffered liver inflammation are too young to have received the jab.
Hepatitis cases have been recorded across the UK as part of the new wave, including 158 in England, 31 in Scotland, 17 in Wales and 16 in Northern Ireland.
The World Health Organization (WHO) previously said there were 348 probable cases of acute hepatitis in children across five regions globally.
Ireland's Health Service Executive said that there have been six probable cases of children with hepatitis in the country.
It said this "is more than would usually be expected over this period of time".
All children were aged between one and 12 years of age, and all had been hospitalised.
