Seventeen people have been arrested as climate protesters block the Port of Dover in Kent.
Insulate Britain said more than 40 of its supporters have targeted Europe’s busiest ferry port.
Several drivers have remonstrated with the activists.
The offshoot of Extinction Rebellion caused chaos on the M25 five times in the past fortnight, but they have been threatened with imprisonment if they return to the motorway.
They also held a demonstration outside the Home Office’s Westminster headquarters.
A spokesperson for the group, which wants the Government to insulate and retrofit homes across the UK to cut climate emissions, said: “We are blocking Dover this morning to highlight that fuel poverty is killing people in Dover and across the UK.
“We need a Churchillian response: we must tell the truth about the urgent horror of the climate emergency.
“Change at the necessary speed and scale requires economic disruption.
“We wish it wasn’t true, but it is.
“It’s why the 2000 fuel protests got a U-turn in policy and gave (Tony) Blair his biggest challenge as prime minister.”
Kent Police said in a statement: “At around 8.20am on Friday September 24 officers were called to reports that a group of people were obstructing the road on Jubilee Way, a second group were at Snargate Street at the junction with A20, and a third smaller group on the A20 at the junction with Aycliffe.
“Officers are in attendance and are engaging with the individuals involved and 17 people have been arrested. The Snargate Street and A20 at the junction with Aycliffe sites are now clear.
“Kent Police is aware of the traffic disruption in the area and is working with partner agencies to minimise delays.”
The Port of Dover handles 17% of the UK’s trade in goods.
It was used by an average of 6,200 road haulage vehicles every day last year.
The blockage comes amid disruption to supplies across the UK due to a shortage of lorry drivers.
The Port of Dover said in a statement: “Port of Dover confirms protesters are currently blocking the entrance to the port.
“Please allow extra time for your journey and check with your ferry operator for updates. The port remains open.”