UPDATE: One of two north-bound lanes is now open and traffic is flowing.
Police have confirmed the truck fire began at 11am today and affected both northbound lanes of the Hume Highway.
Both lanes were shut for an hour while the fire was brought under control, however, one lane has now been re-opened.
Roads and Maritime Services (RMS) staff are now at the scene as a clean-up takes place.
There is a slight traffic delay as motorists merge into one lane prior to passing the burnt-out truck, which is still on the road.
Crews are organising to have the truck removed.
Minor diversions were in place but traffic is now able to use Lane 2 of the Hume Highway, with minimal traffic disruption.
Bowral Police Chief Inspector Brendan Bernie said the cause of the fire would be investigated by police and fire fighters.
EARLIER: A truck fire has closed the north-bound lanes of the Hume Highway at Paddys River.
The road was closed at about 11.17am on Tuesday, October 4.
Live Traffic NSW reports the highway is closed at Sallys Corner Road.
Motorists are advised to exercise caution and avoid the area. North-bound motorists can use the Illawarra Highway, Berrima Road, Taylor Avenue and Medway Road to return to the Hume Highway.