Thousands of supporters of Just Stop Oil have blocked four bridges across the Thames.
Protesters blocked Waterloo Bridge, Westminster Bridge, Lambeth Bridge and Vauxhall Bridge with sit-down protests after marching from 25 points around the centre of London.
Just Stop Oil’s activists said protesters would converge on Westminster, where a crowd led by a samba band had already gathered in Parliament Square. Hundreds had earlier sat on Westminster Bridge, blocking traffic, and moved after police warned them they would be arrested if they stayed.
Among those sitting on Westminster Bridge was Esme Garlake, 26, from London. “I think we are at a real turning point now where the inequalities in our society are so obvious,” she said.
“Today is the day of the energy bills [price rise] coming out and so different groups and grassroots movements are starting to realise that we have to come together to demand social change and climate action.”
Garlake was sat next to her mother, Marilyn Garlake, 59, from Oxford, who said she saw synergies between activism for the climate and cost of living crises. “A tipping point is being reached now,” she said.
“If you look at what’s happening with the cost of living crisis and the climate crisis, everything is coming together, and we have a government that is refusing to take the action that’s needed and making the situation worse.”
The climate activists took to the streets in London as cost of living campaigners Enough Is Enough also held rallies.
The protests come as 200,000 union members walked out of work, with rail unions RMT, Aslef and TSSA, and postal workers’ union the CWU, striking over pay and conditions.
Enough Is Enough, which has been supported by senior figures in the RMT and CWU, as well as prominent leftwing MPs, claims 800,000 people have signed up to support its demands.
It has called for pay rises above inflation, cuts to energy bills, a massive drive to build new homes, support for people who cannot afford food, and more taxes on the richest. Its campaign comes as the government has slashed taxes on the highest earners, and has hinted about massive real-terms cuts to benefits.
On Saturday, the group held rallies in Birmingham, Bristol, Cardiff, Glasgow, Liverpool, Manchester and Norwich.
Just Stop Oil has come into the autumn after a spring and summer of non-violent civil disobedience protests against England’s fuel distribution network.
As part of a coalition of groups, including Insulate Britain, Animal Rebellion, and Jeremy Corbyn’s Peace and Justice Project, it has broadened its demands from an end to all new oil infrastructure to include more taxes on the rich and support with energy bills.
Corbyn, the former Labour leader, drew rapturous applause as he denounced the government’s plans to cut taxes for the richest and benefits for the poorest.
“Our strength is our organisation, our strength is our unity,” Corbyn said. “So let’s stand up for what we believe in.”
Dave Ward, the general secretary of the CWU, said the campaign would pressure the Labour party “into the right place to stand up for working people”.
“Everybody’s job who cares about people in this country to have a fair deal for everything, we have got to build collectivism,” Ward said.
“Are you ready for that? Enough is enough. Let’s get out there: let’s protest, let’s rally. We are going to make change.”
Figures within the Enough Is Enough campaign have told the Guardian there was no coordination between the two groups before Saturday’s protests.