London police dragged away several chanting and singing climate protesters on Thursday who tried to "occupy" an international airport serving the British capital's global financial hub.
Uniformed officers were seen dragging several Extinction Rebellion group demonstrators from outside London City Airport, although there was no immediate official tally of arrests.
Campaigners, some of them in business suits, also staged a sit-in on the platform of the nearby overground train station.
Others unfurled the group's trademark pink banner showing an hour glass -- a symbol of time running out to save the planet from a "climate emergency".
The year-old group backed by Swedish teen activist Greta Thunberg is spearheading a two-week global action that kicked off Monday with partial shutdowns of traffic in cities stretching from Sydney to New York.
In Berlin, protesters blocked a bridge overlooking the Reichstag building.
In London, airport officials said it has managed to remain "fully open and operational" by limiting entrance to the main terminal to ticketed passengers.
"We continue to work closely with the Metropolitan Police to ensure the safe operation of the airport," it said in a statement.
London police reported making 800 arrests in the first three days of protests that included campaigners glueing themselves to the pavement and chaining themselves to cars.
- 'Extermination of life' -
Extinction Rebellion had announced it was planning a "Hong Kong-style" occupation of London City Airport because of the small hub's ongoing expansion plans.
It lies some three miles (five kilometres) east of the Canary Wharf business district -- one of Britain's main financial centres -- and the nearby bustling City of London.
"We are in the streets to make our governments #ActNow and end their complicity in the extermination of life," Extinction Rebellion tweeted as its members were hauled away.
The group's colourful but peaceful protests have managed to attract a mass following since its creation by a group of UK academics studying the effects of harmful carbon emissions on Earth.
Its past big event in London in April managed to shut down central parts of city for 11 days and led to more than 1,000 arrests.
Police are now being more assertive.
The Metropolitan Police on Thursday enacted a rarely-used measure in the 1986 Public Order Act aimed at preventing "serious disruptions to the live of the community".
"Any assembly linked to the Extinction Rebellion 'Autumn Uprising' and those linked to it who wish to continue their assembly MUST go Trafalgar Square and only assemble in the pedestrian area," the police statement said.
"Should you fail to comply with the conditions you run the risk of being arrested and prosecuted."
Extinction Rebellion has vowed to continue targeting the airport until Saturday evening -- and to only wind down their global action at the end of next week.
The group wants governments to adopt policies that cut harmful emissions to a net level of zero by 2025.
Britain has set itself the target of 2050.