A "cluster" of cases of a new, rare inflammatory disease have been detected in south east London, affecting over 40 children and causing the death of a 14-year-old boy.

Dozens of children have been treated in a specialist hospital for a "hyper inflammatory" disease, similar to Kawasaki disease, described as a "new phenomenon" linked to coronavirus.

The Evening Standard has been told that a cluster of cases has now been identified in south east London, focused in Woolwich and Southwark, and one child, a 14-year-old boy with no underlying health conditions, has died.

Hospitals nationwide have been alerted by NHS England to the new disease, after doctors at the Evelina London children's hospital uncovered it, but the numbers of suspected patients remain low.

Dr Sara Hanna, the Evelina’s medical director, told the Standard: “We probably saw the first case in the middle of March. We had a child admitted with something very like Kawasaki – a bit like something we call toxic shock syndrome.

“In the last two weeks, we have just seen this cluster of children where some of them look very like Kawasaki… they have a high persistent fever, they have got red eyes, they have got a rash, they have got swollen hands and feet.”

The doctor said blood tests were not testing positive for the virus in children, but other indicators were "remarkably similar" to those seen in adults with Covid-19.

Also, antibodies indicating recovery from Covid-19 were later found in about half the children and Dr Hanna said the timing of the outbreak was "suspicious."

An article in the Lancet revealed that the first eight cases of the disease at the Evelina concerned children aged between four and 14, and seven required ventilation.

Two tested positive for coronavirus, including the 14-year-old who passed away, and four of the eight were from households with a family member who suspected or confirmed to have had the virus.

Some children had severe abdominal pain and had undergone operations for suspected appendicitis. Others were in “shock” – with very low blood pressure.

A number of still recovering in hospital and some have now been discharged, but similar cases have also been reported north of the river at the Great Ormond Street Hospital.

Dr Hanna said it was vital that children washed their hands regularly and urged parents never to delay seeking medical help if a child became ill.