Officials today confirmed there will be no prosecutions in connection with a Legionnaires' disease outbreak which claimed four lives.

On Wednesday, the Crown Office confirmed there will be no prosecution over the outbreak in Edinburgh, which took place between June 5 and July 15 2012.

During that period, there were 92 cases identified and 45 people had to be treated in hospital.

Four people died from the disease.

Gary Aitken, Head of the Health and Safety Division of the Crown Office and Procurator Fiscal Service said: "Following a complex and thorough investigation which involved detailed genetic analysis we can only conclude that there is no scientific basis for any prosecution related to the deaths and as a result no criminal proceedings are instructed by Crown Counsel.

"This was always going to be a difficult and complex investigation due to the number of potential sources in the Gorgie area but we continued on in the hope that the necessary scientific evidence would come to light.

"Unfortunately that hasn't happened.

"We will now consult further with the families before making any decision in relation to a Fatal Accident Inquiry."

A number of companies are to be prosecuted for health and safety breaches which are unrelated to the deaths.

HSE Head of Operations in Scotland, Alistair McNab said: "This was the largest outbreak in Scotland in the last ten years and one of the most complex HSE has investigated, involving visits to multiple sites and duty-holders including contractors and sub-contractors to check compliance with legionella control standards.

"As HSE and public health experts made clear at the time of the outbreak the source may never be conclusively identified, based on our experience from previous outbreaks.

"Two smaller outbreaks occurred within Scotland during 2013 and again, despite extensive and thorough investigation, the sources could not be proved.

"This can be due to the fact that Legionnaires' disease can have a long incubation period of up to 19 days, so by the time an outbreak is notified to HSE and other regulatory bodies and sampling carried out on water systems, the bacteria levels may have changed or the source producing bacteria may have ceased operation.

"In addition, as a precautionary measure to prevent further ill health when an outbreak is declared, companies are encouraged to shock-dose their cooling towers with chemicals, which again can prevent positively identifying the source."