Sydney CBD Legionnaires' report released

Investigators have been unable to pinpoint the exact source of outbreaks of the deadly Legionnaires' disease in Sydney's CBD this year.

NSW Health on Monday released the findings of its investigation into two outbreaks in March and May that resulted in 13 confirmed infections and claimed the life of a man aged in his 80s.

The life-threatening lung disease is usually linked to contaminated water cooling systems of air-conditioning plants in large buildings.

An expert panel set up by NSW Health has called for tougher regulatory measures to help prevent future outbreaks, including requiring owners to develop individual monitoring and control plans for each cooling tower system.

"NSW Health supports the recommendations in principle, but needs to conduct further consultation on the proposed changes," Chief Health Officer Dr Kerry Chant said.

The department said it expected any regulatory changes to be made in early 2017.