Fire closes part of Princes Hwy in NSW

The Princes Highway south of Sydney remains closed as firefighters work to contain a bushfire.

The M1 has also been closed between Helensburgh and Bulli Tops as the fire, which started at Madden Plains on Friday afternoon, continues.

A water-bombing aircraft has been deployed and firefighters are on the ground battling the blaze.

Motorists are being urged to delay their journeys as traffic in the area is very heavy.