Activists say they will stage a “Hong Kong style” occupation of the terminal building from tomorrow, lying, sitting or gluing themselves in front of the departure and arrival gates at the east London airport.
If they do not make it into the terminal, they plan to blockade it from the outside, in protest against the climate impact of flying and the UK government’s ongoing support of airport expansion.
The warning comes as hundreds of police officers are being drafted in from across England and Wales to help the Metropolitan Police deal with the protests, which are now in their fourth day.
Protesters have been camped, with tents, banners, food stalls and sound systems, on roads around Parliament Square and Whitehall, calling for urgent action on climate change and wildlife losses.
Metropolitan Police Deputy Assistant Commissioner Laurence Taylor said the police have plans in place to intervene and “deal proactively” with anyone who has the intention of shutting down the airport.
And he said more than 80 tonnes of equipment being used for the protests in central London had been seized, including tents, portable toilets and generators.
Police were clearing any sites outside the pedestrian area of Trafalgar Square, after restrictions were put in place to stop disruption in the capital, he said.
Police marched down Horse Guards Road earlier to remove protesters and tents, including several elderly activists who refused to move and were lifted to the side of the road and placed under arrest.
As part of the protests, hundreds of women staged a mass “nurse-in”, breast- and bottle-feeding their babies outside the QEII centre, before marching on Downing Street with their prams.
Lorna Greenwood, 32, who organised the event, said: “We’re bringing the youngest lives who will be affected by the climate crisis to the heart of Westminster.”
Extinction Rebellion protester Dr Larch Maxey said: “The climate and ecological emergency affects us all, so it is essential that we all come together to solve it.
“We cannot do that with a government that is criminally neglecting to tackle the huge problem of aviation.
“Mass peaceful civil disobedience is essential to force our government to take the necessary action before it is too late.”