An "urgent alert" sent out to general practitioners in London in the last three weeks warns of "an apparent rise in the number of children of all ages presenting with a multisystem inflammatory state requiring intensive care" according to a report by the Health Service Journal.

The alert warned that "there is a growing concern that a [COVID-19] related inflammatory syndrome is emerging in children in the UK, or that there may be another, as yet unidentified, infectious pathogen associated with these cases."

A separate alert, sent out by the Paediatric Intensive Care Society, urges doctors to "please refer children presenting with these symptoms as a matter of urgency," according to the HSJ.

The condition has been found both among children who have tested positive for the coronavirus and those that have not.

The symptoms of the condition are "toxic shock syndrome and atypical Kawasaki Disease with blood parameters consistent with severe COVID-19 in children," as well as "Abdominal pain and gastrointestinal symptoms" and "cardiac inflammation."

They report that "This has been observed in children with confirmed PCR positive SARS-CoV-2 infection as well as children who are PCR negative. Serological evidence of possible preceding SARS-CoV-2 infection has also been observed."

The coronavirus pandemic has so far disproportionately affected older patients and the total number of cases of this as-yet-unidentified condition in children remains small.

However, the Paediatric Intensive Care Society has called for an "early discussion" of all new case of the condition in order to identify its origin and limit its spread.

The report comes as UK Prime Minister Boris Johnson comes under growing pressure to re-open the nation's schools following the national lockdown which began in March.

Asked about reports of the new condition, a spokesman for Johnson told a press briefing on Monday that "we are certainly aware of the reports and the Department of Health are looking at that."