A distillery being investigated over the Legionnaires' outbreak has temporarily closed after receiving an official warning for alleged failures in controlling the potentially lethal bacteria.

North British Distillery has received an improvement notice from the Health and Safety Executive (HSE) in relation to one of its air conditioning cooling towers in Gorgie, Edinburgh. The company has since taken all three towers out of operation.

The HSE stressed that the distillery, which can appeal the notice, has not been identified as the source of the outbreak.

It comes as the number of confirmed or suspected cases rose by 13 to 74 yesterday, with one fatality, labourer Robert Air, 56, earlier this week.

A spokesman for North British Distillery, which is part owned by drinks giant Diageo, said: "Our thoughts are clearly with the families of those affected by this situation.

"Ensuring the health and safety of our employees and the local community is our highest priority. On Thursday, June 7, we voluntarily took our cooling towers off-line until the Legionella results from samples taken earlier this week are reported.

"While this precautionary operation is underway we have temporarily ceased distillation.

"Industrial cooling towers remain only one potential source of the infection and North British Distillery is one of a number of sites with such towers. The Improvement Notice issued by the HSE today does not mean that this cooling tower has been identified as the source of the outbreak."

Mr Air worked on a building site yards from the distillery, which is one of six industrial sites being inspected for the legionella bug. Two have not been named but it is understood that one is a defence electronics firm on the outskirts of the city.

The others are Burton's Biscuits, McFarlan Smith pharmaceuticals and Aegon Insurance.

The latest available figures from the Scottish Government state there are 28 confirmed and 46 suspected cases of the disease with the NHS24 phone line receiving more than 500 calls.

It has also been confirmed that four people suffering from the disease, which is airborne, are from outside the capital.

A patient who was originally being treated by NHS Highland has been transferred to the Southern General Hospital in Glasgow, with other sufferers in Tayside, Lanarkshire and Cumbria. All have had recent connections to the capital.

The total being treated in intensive care has risen by two cases to 14.

Dr Duncan McCormick, chairman of the IMT and Consultant in Public Health Medicine at NHS Lothian, said the numbers of patients affected will peak over the weekend and fall away at the start of next week.

He said: "The majority of patients who are presenting now are also on the lower end of the sickness scale and are therefore more likely to be treated in the community with appropriate care than be admitted into hospital, meaning that they are also unlikely to have underlying health conditions."

Health Secretary Nicola Sturgeon said the latest rise in cases had been expected and it was "reassuring" 10 people had been released from hospital.

HSE said that the distillery could appeal the notice.

A spokeswoman said: "The notice was served for a failure to devise and implement a sustained and effective biocide control programme in one cooling tower.

"HSE visited North British Distillery Company Ltd as part of an ongoing investigation into a Legionnaire's disease outbreak in South West Edinburgh. Visits to other companies are ongoing.

"Issuing the Improvement Notice does not mean that this cooling tower has been identified as the source of the outbreak. The source of the outbreak may never be conclusively identified, based on our experience from previous outbreaks."