**Update: Correct as of 12pm, all lanes are closed in both directions.**
The M4 is a nightmare at the moment after a truck and car crash near Prospect.
All citybound lanes had been closed near Reservoir Road but the traffic is now flowing through the breakdown lane.
As a result, all diversions have been lifted.
Two of the three westbound lanes remain closed, with traffic very heavy in both directions.
Motorists are advised to avoid the area or allow extra travel time.
Emergency service crews are still at the scene.