Extinction Rebellion activists have descended on Heathrow Airport, block roads on their way to a mass 'lie-in' blocking access along the A4.

The climate change protestors have filmed themselves cycling towards Heathrow en masse, heading westbound between Hammersmith and Hogarth Roundabout and causing delays.

The large group of cyclists say they have created a cycle superway on the M4 in protest against the Heathrow airport expansion, and are shown taking up several lanes on a road near the airport sporting XR flags.

Boris Johnson said he'd block Heathrow airport expansion by lying in front of the bulldozer.



He's an MP, he could have blocked it in parliament.



He didn't.



Now the bulldozer's coming.



Boris Johnson must block Heathrow. RT to agree.#XR #ExtinctionRebellion pic.twitter.com/Eo7w98fnu6 — Extinction Rebellion London (@XRLondon) December 8, 2019

In the tweet, Extinction Rebellion say that Boris Johnson said he'd block the expansion by lying in front of the bulldozer, but failed to block the plans as an MP.

The cyclists, who TfL Traffic warned were causing delays across south London, were spearheaded by a yellow "bulldozer" tricycle.

The Met Police imposed pre-event conditions upon the demonstration on Friday, stating that Sunday's planned activities "have the potential to cause serious disruption to London's communities."

Commander Dave Musker, Gold commander for the policing operation, said: "This is an exceptionally busy time for Heathrow in the run up to Christmas and the travel plans of many, many people may have been disrupted.

“The police must balance the rights of Londoners and those visiting the capital to go about their daily lives without serious disruption with the right to peaceful protest.

"After careful consideration I have made an operational decision to request the authority from my Assistant Commissioner to implement conditions on this demonstration based on the information available to me.

"If you wish to take part in this planned activity on Sunday, I ask that you do so lawfully and within the restrictions set out above. Anyone breaching these conditions will be liable to arrest and prosecution. I have directed that we will be proactive in robustly enforcing these proportionate and necessary conditions.”

The demonstration is part of Extinction Rebellion's 12 Days of Crisis campaign which aims to put pressure on the political parties to make “climate and ecological emergency the defining issue of this general election.”

A lie-in is currently taking place with hundreds of people involved in the 'Bikes against bulldozers' protest.