Four Navy members were exposed to low levels of carbon monoxide today, alongside at Garden Island in Sydney.

The incident was immediately contained. As a standard precautionary measure the fire brigade and ambulance service were called.

The personnel were assessed on site with two immediately released and two subsequently taken to hospital for observation. These two have been released and all are expected to return to work tomorrow.

There is no further threat to Navy personnel or the local community and the affected personnel will continue to be monitored.

Defence will investigate the circumstances of the incident and appropriate corrective measures have been taken to ensure the ongoing safety of personnel.