Southbound lanes on the Princes Highway are closed at Holt Road in Sylvania due to a gas leak.
The Transport Management Centre has advised motorists to avoid the area and use Port Hacking Road or Rocky Point Road instead.
Traffic in the area is heavy, with motorists experiencing significant delays.
All northbound lanes on the highway remain open at this stage.
Emergency services and utility company crews are responding.
For the latest traffic information, visit www.livetraffic.com or call 132 701.