Hundreds of Extinction Rebellion protesters have blocked Whitehall in a protest against HMRC’s links to Barclays Bank, which handles the government’s tax collection bank accounts.

On the second day of the environmental protest group’s latest campaign of protest and civil disobedience, activists from its Welsh chapter locked themselves together in the street in front of the tax collection department, stopping traffic.

They displayed banners saying, “Government in bed with climate criminals”, “Trethi i Barclays = Llifogydd yng Nghymru (Taxes for Barclays = Flooding in Wales)”, and, simply: “HMRC stop banking with Barclays”.

As a helicopter buzzed overhead, a lone horn player played the Imperial March from Star Wars. Activists sat in the road eating cake. Others holding XR flags engaged passersby, handing out stickers and telling them about their reasons for staging the protest. Protesters dressed as cleaners scrubbed the front doors of HMRC, as a banner reading “Our taxes fund climate chaos” was stretched out in front of them. Occasionally, a protester was carried away by police.

HMRC uses Barclays’ payment solutions to process national insurance and self-assessment tax payments, child benefit repayments and a range of other HMRC transactions, according to XR. Protesters in Whitehall said they understood the bank to have funded fossil fuel industries to the tune of billions since the Paris climate accords were adopted in 2015.

Pam Williams, 73, from Llanidloes, was locked together with another activist, their arms linked in a wooden box, outside the main doors to HMRC. Williams, a former organic farmer, said she had only learned about Barclays’ links to the UK government’s tax collectors through a close reading of her self-assessment tax return form.

What concerned Williams was the “embeddedness” of fossil fuel finance with the state. “We can choose which banks we have, but we can’t when we pay our taxes,” she said. “These are paid on our behalf to an evil bank.”

David Kilner, 34, from Cardiff, stood atop an oil drum. Two women were locked together by their arms through holes in the barrel. Kilner wore an oil bottle on his head and rubbed replica banknotes together with black-stained hands.

“I’m dressed up as one of the many multinational oil industry executives – oilheads, petrolheads,” he said. “This protest is called ‘Not in Our Name’. In Wales, we have suffered great flooding, repeatedly, across our nation. And this extreme weather that’s causing this flooding is undoubtedly just a sign of things to come.”

According to XR, activists in Wales supported the protests in London by taking action outside local Barclays branches. Activists in Cardiff stood outside William Morgan House, the new HMRC building in Cardiff, to hand out leaflets and tell HMRC staff about Barclays’ role in the climate crisis.

At the same time as the HMRC protest, another group of older XR protesters had gathered in London Bridge for a “Make our pensions green” demonstration. A further demonstration targeting the fashion industry was planned for later in the day, while XR coordinators hinted on the messaging app Telegram that another street occupation was also planned.

The Metropolitan police said in a tweet: “Protesters are blocking roads around Parliament Street and Whitehall in Westminster. We have officers on scene. Their demonstration is causing disruption to traffic which we are working to minimise.”

In Covent Garden on Tuesday morning, police were still dismantling the pink table structure dropped into place by XR protesters on Monday afternoon. The Met said: “Overnight we have continued to clear the roads around Extinction Rebellion’s protest on Long Acre junction, Covent Garden. We’ve removed the chairs activists brought and glued on to, making many arrests. At this time the pink table structure remains.”

The force said it had made 52 arrests related to Monday’s protests, and 10 related to an XR protest on Sunday.