Eco-activists Just Stop Oil have resumed their 12th day of action by climbing on top of police vans at the back of Downing Street.
The campaign group unfurled banners at the rear of the address with their campaign group's name written on them.
This comes after the environmentalists were accused of blocking emergency vehicles yesterday while protesting in central London, forcing an ambulance to reverse and find another route through the capital.
Police Commissioner Sir Mark Rowley told the London Assembly Police and Crime Committee that officers have to wait until protests by Just Stop Oil and Animal Rebellion are deemed to meet a legal threshold of causing major disruption before they can be shut down.
His officers are in touch with Transport for London, local councils and the emergency services several times per day to check the level of disruption caused.
Sir Mark said: 'Over the last 11 days, all of those partners have been of a view that it doesn't cause serious disruption.'
He went on: 'As soon as we have evidence of that serious disruption either being crossed as a line, or a good prospect of it being crossed, we'll start being more assertive with our powers.'
In a video released by Just Stop Oil, one onlooker appeared emotional as she praised the group saying 'It's really amazing work, and they are so brave for being out here with cars coming at them, especially, and cars, yeah, willing to stay there for everyone else and it's really nice work.'
Yesterday's traffic chaos, which began at 10am and involved 32 of the group's activists, caused marooned drivers to get out of their cars and angrily remonstrate with the protesters - some of whom had glued themselves to the road.
The Metropolitan Police later confirmed officers arrested 28 protesters in the demonstration, all on suspicion of wilful obstruction of the highway. They were taken to various Central London custody suites, where they remain.
One taxi driver was filmed saying: 'How do I pay my bills? I've got one of these, an electric taxi. I paid £70,000 for that. I'm doing my bit, so why do you stop me?' The activist's answer could not be heard, but the driver replied: 'What you're asking for is years and years and years away, it don't happen overnight. How stupid are you?'