The Transport Management Centre has advised motorists travelling west on the M4 to expect significant delays due to a multi-vehicle accident just past the M7 in Eastern Creek.
Two of three westbound lanes were closed after the accident, but have since been reopened.
Traffic remains very heavy in the area.
Emergency services and Roads and Maritime Services crews are at the scene working to clear the accident as quickly as possible.
Motorists are advised to avoid the area or use the Great Western Highway as an alternative route.
Delays are expected.
For the latest traffic information, visit www.livetraffic.com or call 132 701.