THE M4 was closed with stationary traffic in both directions between Junction 10 A329(M) Wokingham and Junction 8 after a lorry overturned.
Fuel spillage over both carriageways near Maidenhead means that the motorway was closed in both directions while a clear-up operation takes place.
The M4 eastbound has now been reopened but police are advising drivers to avoid the area.
One man from Swindon said that he was sitting in his car with the engine off having been told the motorway would be closed for at least another hour.
A diversion in operation via the A4, A3290 and A329M.
Highways England reported that an air ambulance had now left the scene.
It said traffic conditions were not expected to return to normal until at least 5.30pm.
Thames Valley Police have now said that the westbound M4 will be shut for at least 10 hours although the eastbound carriageway has now reopened.
#M4 Eastbound J10 - J8 Air Ambulance has departed. Traffic released, lanes 2 and 3 remain closed following the overturned HGV.
— Highways England (@HighwaysEAST) October 12, 2016
The westbound carriageway of the M4 at J 8/9-10 will be shut for at least ten hours. Eastbound carriageway has now reopened. Avoid if poss.
— TVP Roads Policing (@tvprp) October 12, 2016
Yesterday the London-bound M4 between junctions 11 and 10 was closed for hours after a pedestrian died in a crash involving a lorry early that morning.
The M4 was closed while Thames Valley Police investigated the circumstances of the crash just before 3am.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article