Ditchling Road has been closed due to a police incident.
Traffic reports say the road has been closed both ways from Coldean Lane (Old Boat Corner) to Ditchling Beacon Car Park.
A police spokesman said the road has been closed after a piece of ordnance was dug up in a nearby field.
According to police, the Explosive Ordnance Disposal team is on scene.
Police could not confirm when the road would reopen.