Hundreds of police officers have closed in on Extinction Rebellion protesters in central London as demonstrations entered a fifth day.
Officers surrounded a pink boat in Oxford Circus as actress Dame Emma Thompson told activists her generation had “failed young people”.
More than 570 people have been arrested at protests this week in Oxford Circus, Parliament Square and Waterloo Bridge
Dame Emma joined the protests after flying from Los Angeles on Thursday.
She said: “We are here in this little island of sanity and it makes me so happy to be able to join you all and to add my voice to the young people here who have inspired a whole new movement.”
It comes as a small group of demonstrators staged a protest at Heathrow Airport amid threats to disrupt flights over Easter.
Protesters stood by the tunnel leading to Heathrow Terminals 2 and 3, but all roads remain open.
However, Robin Ellis-Cockcroft, 24, said the group had succeeded in creating an “emotional disruption” at Heathrow, adding that no further Extinction Rebellion protests would take place on Friday.
Protests are still being held at Waterloo Bridge, Oxford Circus and Parliament Square, but the Met Police said officers have been working 12-hour shifts and have had leave cancelled.
Ken Marsh, chairman of the Metropolitan Police Federation, said: “This is very, very difficult for us because my colleagues have never come across the situation that they are faced with at the moment.
“They are dealing with very, very passive people, probably quite nice people, who don’t want confrontation whatsoever with the police or anyone else but are breaking the law.”
Environmental activists have also been in action in other parts of the world.
In Paris, they blocked the entrance of the Societe Generale bank headquarters, as part of a protest urging world leaders to act on climate change.
Pepper spray was used by anti-riot police in an attempt to disperse the demonstrators.
Activists also gathered outside the Ministry of the Ecological and Inclusive Transition in La Defense, near Paris, and blocked the entrance of the headquarters of French oil giant Total there.