A Just Stop Oil campaigner was arrested ahead of a mass demonstration after breaking court bail by preparing to march.
The climate group say the protester was detained in Jubilee Gardens after being remanded to prison overnight last week.
A video shows police carrying the eco-warrior away and putting him in the back of a police van.
Chants of “shame on you” could be heard as police carried the man away.
Around 500 people are said to have taken to the streets calling for an end to new oil and gas.
In a post on social media, Just Stop Oil has said: “500 people from Just Stop Oil, @corbyn_project, @XRebellionUK, and @CClimateAction are marching from Jubilee Gardens to end new oil and gas.”
The Met Police said the demonstrators are using Fleet Street instead of the Embankment and are not marching slowly.
A spokesperson said: “There are around 250 people taking part. They’re moving at a normal speed which is different from other JSO ‘slow marching’ action.
“Officers are with the group. Should they slow down or stop in the road with the intent to cause serious disruption we’ll take appropriate action.”
Yesterday, 16 JSO protesters were arrested, the Met have said.
One of those stuck in traffic included an ambulance on blue lights.
A spokesperson from the Metropolitan police said: “We are arresting Just Stop Oil activists causing disruption in Whitehall.
“These arrests are being made swiftly so we can release the traffic, which includes an ambulance.
“Officers have arrested all of the activists slow marching in Whitehall.
“Another ambulance, which is on blue lights, is stuck in the disruption this slow march has caused.
“All 16 of the activists have been arrested and their way to custody.”