Extinction Rebellion protesters are planning to "shut down" Heathrow Airport tomorrow, according to a leaked WhatsApp message.
Activists, who have blocked roads, transport and landmarks for the last four days, said they were "raising the bar" to target the busiest airport in the UK ahead of the long weekend.
With at least 100,000 people expected to fly from Heathrow on Good Friday, any demonstrations will cause widespread chaos for Brits attempting an Easter break.
The message, which began 'Dear rebels', said: "Tomorrow we raise the bar. We are going to shut down Heathrow.
"There is a deep remorse for those whose holiday and family plans will be disrupted tomorrow. It is not our intention to cause further separation."
Do you know anything about the plans? Contact webnews@mirror.co.uk
The message continued: "However, the aviation industry needs to be targeted and we are all aware of the deep, structural change that needs to come."
Screenshots of the plans were leaked online.
When Mirror Online contacted Extinction Rebellion for comment, a representative would not confirm or deny the plans.
Organisers behind the climate change protest which has brought parts of central London to its knees have previously said they are prepared to escalate the group's tactics if their demands "are not met".
Dr Gail Bradbrook, a co-founder of the Extinction Rebellion (XR) group, said demonstrators would continue to act despite the first people being charged over the disruption.
It has seen activists glue themselves to public transport and block bridges and major roads across the capital.
The fourth day of protests began with a challenge to Environment Secretary Michael Gove to meet with activists at Parliament Square to find a solution to the issue.
And organisers said they expected even more people to join the protests, with a statement - which was later deleted - adding: "Easter Weekend is tomorrow and thousands more rebels will join.
"Police struggle to arrest 350 and there are ten times that number prepared to be arrested.
"The hollowed-out British state is overwhelmed."
Speaking from Waterloo Bridge, Dr Bradbrook said the group has had "very heated discussions about what's for the best" in terms of its methods.
"It's certainly an option that tactics will be escalated if our demands are not met," she said.
The news of Heathrow Airport's potential shut down came as police began charging people over the protests in London, following 428 arrests by the Metropolitan Police since Monday, according to the latest figures.
