THE source of a salmonella outbreak remains a mystery more than two weeks after a nursery was forced to close.

Three children from Cannock House Nursery, Hawstead Lane, Chelsfield, were hospitalised with diarrhoea during the weekend of March 17 and March 18.

They were identified as having salmonella enteritis and 146 other people have tested positive, including staff and parents.

Health Protection Agency (HPA) staff and Bromley Council's environmental health officers are still investigating and have not yet found the source of the outbreak.

The HPA also ran specialised tests to see if an unusual strain of the potentially lethal E coli bug was involved.

It did this because the symptoms the children were displaying were consistent with those of E coli 0157.

But the tests for this virus came back negative.

South East London Health Protection Unit director Dr Rachel Heathcock said: "As a precautionary measure, the nursery was closed on March 19.

"Results confirmed salmonella infection was the cause of the outbreak.

"Investigations into the source of the salmonella bug are ongoing."

She added: "Appropriate infection control measures were immediately put in place to stop the spread of the infection."

The nursery is also currently being investigated by Ofsted to find out if it meets acceptable care standards because of the outbreak.