The source of the outbreak of E. coli O157 in which a three-year-old child died was Dunsyre Blue cheese an investigation has found, but its producer says more detailed investigations are needed.

The operators of Errington Cheese the South Lanarkshire manufacturer of the product say the report confirms their fears that the cheese was the only food stuff considered from an early stage in the investigation, and that there was still no microbiological evidence that Dunsyre Blue caused the outbreak.

Health Protection Scotland (HPA) investigated the outbreak in which a total of 26 cases of the same strain of E. coli O157 were identified between July and mid-September last year. Its focus came to centre on Errington Cheese and its production processes at its Carnwrath base.

Dr Alison Smith-Palmer, chair of HPS's Incident Management Team (IMT), said: "The report describes the detailed epidemiological, microbiological, food and environmental investigations and concludes that Dunsyre Blue cheese was the source of this outbreak. It also presents lessons learned and recommendations for improvement."

The report concludes that: "Potentially pathogenic E. coli were able to enter and survive the cheese production process at the food business.

"Positive results were obtained for cheese produced over a period of four months, indicating a systematic potential for Escherichia coli (STEC) to enter the process and contaminate final products."

It added: "Extensive investigations concluded that the source of the outbreak was the consumption of Dunsyre Blue.

"This conclusion was based on evidence from epidemiological and food chain investigations and supported by microbiological evidence and deficiencies identified in the procedures for the monitoring and control of STEC at the food business."

Another cheese from Errington Cheese, Corra Linn, was also later found to contain potentially pathogenic E. coli.

Food Standards Scotland (FSS) chief executive Geoff Ogle said he was satisfied that the evidence and conclusions presented in this report fully justified the decisions the organisation had taken to protect consumers.

"All of our decisions and actions were taken with the sole aim of protecting public health.This report should allay any concerns with regards to our decisions and assure others that our actions were evidence based. That will always be the case," he said.

Humphrey Errington, the founder of the cheesemaking company, had gone to the Court of Session earlier this year to overturn a sales ban by FSS.

His company issued a statement yesterday saying all their concerns regarding the investigation remained.

"We believe that more detailed investigations into the cause of the outbreak are needed. This is particularly in relation to those cases where HPS were unable to find any direct link to Dunsyre Blue."

It added: "There is no microbiological evidence that Dunsyre Blue caused the outbreak - all they have concluded is that raw milk cheese carries a small risk of STEC which is already well recorded in scientific literature; there has been no highly pathogenic STEC found in any of our products, nor anything found linking our cheese to the outbreak. This is fact."

It questioned what data had been submitted to the inquiry."We have been denied this information repeatedly, both under freedom of information requests and through legal channels. We will continue to seek access to the epidemiological evidence as it is crucial.

"The report confirms our fears that blue cheese was the only food stuff considered from an early stage in the investigation. Salad was also mentioned but there is no evidence given of any investigation of salads."