West Sussex Fire and Rescue Service (WSFRS) said it was called to reports of a heavy goods vehicle on fire on the A23 at 5.30pm.
The road is closed southbound between Handcross and Slaugham.
A WSFRS spokesperson said: “Joint Fire Control mobilised four fire engines and a water carrier to the scene. Upon arrival firefighters wearing breathing apparatus quickly got to work extinguishing the fire.
“The A23 southbound remains closed at this time and is likely to remain so for some time. The northbound carriageway remains open. Drivers are encouraged to avoid the area.”
An alert on AA Traffic News reads: “Partially blocked and queueing traffic due to lorry fire on A23 Southbound from the B2110 to B2115 / Staplefield Lane.”
Delays of around an hour have been reported southbound between B2110 and B2115.
Motorists on the M23 southbound, between J10A B2036 Balcombe Road (Crawley South / Balcombe) and J11 A23 (Pease Pottage), have also reported delays of around ten minutes.
5. West Sussex A23 closed following lorry fire
West Sussex A23 closed following lorry fire Photo: Sussex News and Pictures