The climate protesters have also covered News UK’s headquarters and the Bank of England with paint in a wave of action in central London on Monday morning.
The group said the buildings were chosen to represent the pillars that support and maintain the power of the fossil fuel economy.
Just Stop Oil has vowed to protest every day this month in a call for an end to all new oil and gas licenses.
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Scotland Yard said protesters threw paint in a number of locations, naming Marsham Street, Millbank, London Bridge and Threadneedle Street on Monday morning.
“Officers responded quickly to all incidents and a number of people have now been arrested on suspicion of criminal damage,” the force tweeted.
City of London Police confirmed two people had been arrested outside the Bank of England.
Videos shared by Just Stop Oil showed bright orange paint sprayed over the glass entrance to News UK’s building in London Bridge, which is home to The Times, The Sun and Talk Radio among other media outlets.
They also show an activist being carried away by someone in a high-vis jacket after spraying paint over the Home Office.
Another video shows a protester spraying orange paint over the Bank of England, while another writes “Just Stop Oil” on the building nearby.
A spokesperson for the group said on Monday: “We are not prepared to stand by and watch while everything we love is destroyed, while vulnerable people go hungry and fossil fuel companies and the rich profit from our misery.
“The era of fossil fuels should be long gone, but the creeping tentacles of fossil fuel interests continue to corrupt our politics, government and the media, as they have for decades.”
They added: “Well we’re done with begging. We are acting to stop new oil and gas because it is the right thing to do.”
Last week, activists were arrested after throwing chocolate cake in the face of a waxwork statue of King Charles III at Madame Tussauds.
Its protesters are also blocking roads around the capital - with some gluing themselves to the tarmac. Earlier this month, two climbed up a bridge over the Thames to block the key crossing over the river.
Additional reporting by PA