The Transport Management Centre said northbound traffic remains heavy.

9.20am: One northbound lane has reopened on the M1 Princes Motorway after a car fire near Picton Road.

Two northbound lanes remain closed.

Drivers are facing significant delays with traffic queued back 5 kilometres.

Earlier: A car fire has closed northbound lanes on the M1 Princes Motorway (Mount Ousley Road) on Monday.

The car is at the top of Mount Ousley near the Picton Road turnoff.

Drivers are advised to use Bulli Pass as an alternative.

All southbound lanes remain open.

Emergency services and traffic crews are on site.

More to come