The group unfurled a banner urging the government to "stop funding climate death" and said they had fired 1,800 litres of the "blood" at the central London building - although most appeared to have ended up on the street and pavement.
While standing on top of the fire engine, protesters struggled to control the hose as it whipped around on its own accord.Massive failure for radical climate change activists with @ExtinctionR who lost control of a fake blood hose outside the Treasury in London. Four people were arrested for criminal damage. Footage published by the BBC. #ExtinctionRebelion pic.twitter.com/dbgGJMEM4v
— Andy Ngo (@MrAndyNgo) October 3, 2019
Police later turned up to protect the building and four people were arrested on suspicion of criminal damage.
Campaigners said the fire engine they used is out of commission and the fake blood made with food dye that can be washed off.
Extinction Rebellion said it wanted to highlight the "inconsistency between the UK Government's insistence that the UK is a world leader in tackling climate breakdown, while pouring vast sums of money into fossil exploration and carbon-intensive projects".
Protester Cathy Eastburn said the Treasury's decisions had "devastating consequences" and included "huge subsidies for fossil fuels, financing massive fossil fuels projects overseas [and] airport expansion".
However, one government tsar has said Extinction Rebellion's eagerness to cut the country's emissions by 2025 would do more harm than good.
Dieter Helm, chairman of the natural capital committee advisory group, said the net-zero target would mean an increase in pollution through imports.
The University of Oxford professor said the it would do "a hell of a lot of damage" as carbon emissions would just be created elsewhere.
Prof Helm believes instead that a carbon tax should be introduced and those who contribute to a net reduction in pollution should receive payments.
