Protesters demonstrating about climate change have blocked a tunnel leading into Heathrow Airport, bringing traffic to a standstill.
The blocked tunnel leads to Terminals 2 and 3, which are used mainly by long-haul airlines including Virgin, United, Delta, Emirates, Air Canada, Singapore Airlines and British Airways.
However, passengers trying to reach all five terminals have been affected as traffic was backed up along the M4 motorway by 9:30 this morning.
In addition, the M4 spur road southbound was also closed and the A4 Bath Road was also affected by sever traffic jams.
Heathrow Airport is advising passengers due to fly today to leave extra time to reach the airport.
Any passengers who are able to do so should consider reaching the airport by train.