Careshare, which has 21 nurseries across Scotland, has also been advised it will face a series of spot checks to ensure staff are doing everything they can to prevent the spread of infection.

Nine cases of E.coli 0157 have been confirmed so far. All of them are linked with the Careshare Nursery at Lauder, which closed voluntarily a week ago after a number of children became sick.

Four remain in a stable condition at the Royal Hospital for Sick Children in Glasgow, where they are receiving treatment for kidney failure.

Public heath officials have admitted the source of the outbreak may never be found, but investigations are continuing.

The Dundee-based Care Commission’s Director of Children’s Services Regulation, Ronnie Hill, held an urgent meeting with executives from Careshare.

This follows a meeting last month when Care Commission staff told the firm’s operational director of shortcomings at the Lauder nursery, including infection control issues.

In January, the nursery was ordered to improve its infection control procedures, after Commission inspectors uncovered flaws.

Now Mr Hill has revealed a review of all inspections carried out at other Careshare nurseries in the past year showed nine out of 19 nurseries checked had been criticised on hygiene or infection control issues.

These included another facility in Dunfermline (Carnegie), where there was a recommendation following checks in December to ensure health and hygiene policies are properly implemented and monitored.

A nursery at Croftbank, Kinross, was told to review existing infection control after an inspection the same month.

Among other nurseries operated by Careshare are Meadows Nursery in Monifieth and Pinewood Nursery in Glenrothes.

Mr Hill added, “We have told Careshare we’ve made the same type of recommendations relating to hygiene or infection control in half of their nurseries.

“These issues have been made clear to the individual nurseries, but we have already met with Careshare twice this year and have made it very clear this must be addressed at a national level.

“We have advised the company we will be making a detailed study of its central policies and overall practice on infection control.”

Careshare operates its own infection control measures as part of its Best Practice Manual in Hygiene and Housekeeping, which all of its staff are to follow.

Mr Hill added, “Our specialist infection control adviser is taking a very detailed look at the manual and will then give our comments to Careshare.

“We will be carrying out a series of unannounced inspections at all of Careshare’s services, specifically to look at infection control policies and practice.

“Senior managers in Careshare are co-operating fully with us and have underlined their commitment to making sure all staff are aware of their obligations.

“These measures are being taken because we have looked closely at the operation of all Careshare nurseries in Scotland in the context of this outbreak.”

Jonathan Bell, Careshare’s operations director, said, “We welcome this review from the Care Commission and are co-operating fully.

“We will implement any new guidance immediately across all our nurseries.

“As Scotland’s biggest operator, we are very confident standards of care at our nurseries are above average and that our staff are extremely professional.

“We hope all nurseries, council and private, can learn valuable lessons from this episode in order to reassure parents that nurseries are clean and safe.”

* Environmental services and an infection control nurse are visiting a second nursery at the centre of west Fife’s E.coli outbreak today to check all is well and provide any advice if necessary.

Dr Charles Saunders, the consultant in public health medicine with NHS Fife, said, “We have done a risk assessment and feel the risk of further cases is, while not zero, significantly low that it would not be either justified or proportionate to close the nursery.”

It has emerged two more children at Lynburn Nursery may have the E.coli 0157 bug. Another child was confirmed as having the potentially deadly infection on Monday.

Health officials said the number of confirmed cases remained at nine — all of whom have links with the independently-run Careshare Nursery in the grounds of Lauder College, which closed voluntarily a week ago after a number of children there fell ill.

The child at Lynburn confirmed as having the infection also attended Careshare.

A further 28 people regarded as possible cases are being monitored at home, although Dr Charles Saunders stressed health experts involved in the screening process were erring on the side of caution.

“We have set a very, very broad definition of what a possible case is, the idea being we will pick up everyone who has got it but also people who don’t,” he said.

He said it would be extremely unusual for a significant number of the 28 possible cases to have the bug.

The Careshare nursery will remain closed until the Care Commission and environmental services agree it can re-open, but Lynburn will remain open.

Staff at Lynburn have been handing out letters and leaflets to parents of children attending nursery and information will be posted to those whose youngsters were not present.

Dr Saunders said everything possible was being done to identify the source, but admitted it may never be found. NHS Fife has already said the bug was unlikely to have been caused by either food or drink.

The incident control team will meet again today to continue the investigation into the possible cause of the outbreak. A freephone helpline for those affected is open from 8 am to 10 pm every day on 08000 28 28 36.

Lauder College principal, Professor Bill McIntosh, praised the work of experts trying to find the source of the outbreak.

He said, “Given the latest official EHO statements it would appear this outbreak may have been brought in from an external source.

“We would like to express our praise for the ongoing hard work of the various health agencies investigating the situation.”