Updated at 6.30pm: Health authorities in Hong Kong on Friday afternoon were investigating an outbreak of painful infections which have been striking new-born babies. The Health Department?s Centre for Health Protection (CHP) has reported a cluster of necrotising enterocolitis on three new-born babies. A CHP spokesman explained that necrotising enterocolitis, or NEC, was an unpleasant infection, where dead tissue in the lining of the small intestine needs to be surgically removed. The disease, mainly seen in premature and low birth-weight babies, could have a number of causes, he said. But in many outbreaks, the causes of the disease cannot be identified. The spokesman revealed that three new-born babies, including two premature babies, had developed NEC symptoms between May 27 and June 7. They were treated in the Neonatal Intensive Care Unit of Pamela Youde Nethersole Eastern Hospital. The babies were in a stable condition and still under isolation on Friday afternoon. The spokesman said that following the latest outbreak this week, CHP staff launched epidemiological investigations. They have also stepped up infection controls in hospital wards. On Friday, staff revisited wards and took samples for laboratory tests. He said new admissions to the Neonatal Intensive Care Unit have also been suspended. No similar case had been reported at other public hospitals. The Hospital Authority had informed all public hospitals about the outbreak, the spokesman said. 'Appropriate measures have been implemented and we are closely monitoring the situation,' he added.