Two of the cases have been linked to the Barrow-in-Furness outbreak, which has claimed the lives of three people.

One case in Glasgow is understood to involve a 56-year-old man from the Clydebank area of the city, who had been working in the Cumbrian town.

He was tested at Glasgow's Gartnavel General Hospital to see if he had the potentially-deadly disease.

We have taken immediate steps to thoroughly investigate the possible cause of the third case

Dr Maida Smellie NHS Ayrshire and Arran

A Glasgow woman has also been recovering in hospital in the city after contracting the bug.

A spokeswoman for NHS Greater Glasgow said: "We have a second confirmed case of Legionnaires' in Greater Glasgow which has firm links with Barrow-in-Furness.

"However, this is not a cause for public concern because the infection is not transmitted from human to human."

A third case was reported in Ayrshire after a resident developed symptoms of the disease while on holiday abroad.

Trace the source

Dr Maida Smellie, consultant in public health medicine at NHS Ayrshire and Arran, said: "Last night we were notified of a third case of Legionnaires' disease in an Ayrshire resident.

"We have taken immediate steps to thoroughly investigate the possible cause of the third case.

"Given the dates that the person was abroad, it is more than likely that the disease was contracted while on holiday."

Meanwhile, health bosses in Ayrshire have been continuing efforts to trace the source of another two cases of Legionnaires' disease, which last month claimed the life of one Ayrshire man and left a woman seriously ill.