Nearly 300 probable cases of children with severe hepatitis have been detected in 20 countries worldwide, with some in South East Asia, the World Health Organization (WHO) has said.
Health officials around the world are investigating a mysterious increase in cases of the liver condition which was first spotted in the UK.
A common virus called adenovirus, which has rebounded after the pandemic, could be causing the surge.
One death has been reported by the WHO.
As of 1 May, it said most cases of young children with hepatitis had been detected in Europe with small numbers also reported in the Americas, western Pacific and South East Asia.
The first cases of this unusual hepatitis were spotted in Scotland in children under the age of 10. More than 140 cases are now being investigated in the UK.
Most UK children had a mild form of liver inflammation, although 10 children have needed a liver transplant.
They had initial symptoms of vomiting and diarrhoea followed by yellowing of the skin or whites of the eyes, called jaundice.
The hepatitis viruses that normally cause the condition (viruses A, B, C, D and E) were not detected in any of the children.
Countries worldwide started looking for the unexplained liver condition ‘of unknown origin’ in children after it was highlighted by UK health officials.
There is no reason to believe the rare condition itself is spreading around the world.