Bacteria which can cause deadly Legionnaires' disease was found in the water supply at the Scottish Parliament seven months ago, it was revealed today.

Officials insisted there had been "no risk" to anyone in the Holyrood building and said the contaminated source was immediately isolated and cleaned following tests in June last year.

The bacteria was found in two "seldom used" water outlets, not drinking taps, and traced back to a hot water tank inside 17th-century Queensberry House, officials said.

The tank supplies water to the historic block and a building on the Canongate side of the Parliament in Edinburgh.

MSPs on Holyrood's Housekeeping Committee, the Corporate Body, were told about the find last week.

Tory MSP Alex Johnstone, who sits on the committee with MSPs from all main parties, said: "I'm happy it was dealt with at the time. It's been taken as a lesson for the future.

"I'd be surprised if anything like this happened again."

The bacteria - which can be found naturally in hot and cold water - can lead to flu-like symptoms, fever and pneumonia, if inhaled through vapour.

Officials issued papers today describing how the infection was treated.

The isolated tank was disinfected, and subsequent tests have all proved clear.

The Parliament said a risk assessment was carried out by "external experts" and completed last month.

It recommended weekly flushing of showers, removal of under-used showers, more testing for legionella bacteria and extra cleaning.

A Scottish Parliament spokesman said the findings were not revealed to MSPs because the risk was "not considered critical".

"We are fully satisfied the measures taken ensured the risk to building users was controllable at all times," the spokesman said.

"The affected areas have produced clear readings for the last four months and legionella has not been detected anywhere else within the building during our regular testing."

He added: "The Corporate Body was satisfied it had been well handled by officials and was supportive of the actions taken .

"However, members of the Corporate Body were disappointed that the matter had not been brought to their attention at the time."

The spokesman said the contaminated water did not connect to areas open to the public.

The Parliament also took the advice of Ken Ashley, lead author of the Health and Safety Executive's guidance on the management of legionella risk.

He said: "This was not a high risk situation at any time."