Dozens of arrests were made as thousands of people attended rallies in central London, Cardiff and Manchester on Tuesday, after actions planned for earlier in the year were cancelled due to the coronavirus pandemic.

At least 10 activists were carried away by officers when a group refused to move from a road next to Parliament Square which had not been sanctioned for a sit-down protest by police. Scotland Yard later confirmed that 65 people had been arrested on suspicion of public order offences by 4pm.

Stunts planned for the days ahead include a “carnival of corruption” outside the Treasury, a “walk of shame” near the Bank of England and a silent protest outside Buckingham Palace.

Activists told The Independent the scale of the crisis meant it was necessary to “take to the streets” and use methods of civil disobedience – despite concerns about the spread of Covid-19.

“Every time someone finds a reason why we shouldn’t be doing this, but we can’t ignore the scale of the crisis – the crisis is here now,” said 17-year-old Cat Savage, who starts sixth-form college in Herefordshire in a few days’ time.

“We have very limited time left and we have to get on with creating a new world, right now. I should not have to be here – children shouldn’t have to do this. But we seem to be taking the lead because our political leaders are not taking it seriously.”

She added: “The government has shown it can change things during the pandemic. So we need them to do the same for the climate crisis.”

Davina Malcolm, 73, travelled to London from rural Hertfordshire to join the mostly young protesters – the very first time she had left her village since lockdown began.

“I thought it was so important to send a message to government that they need to start taking the crisis seriously,” she said from behind a plastic face visor. “The government is not treating this like the emergency it is. I have two young grandchildren and I want things to change for them.”

Activists are urging MPs to support the Climate and Ecological Emergency Bill set to be tabled by Green Party MP Caroline Lucas on Wednesday.

The legislation would toughen targets set in the 2008 Climate Change Act by including carbon emissions from international trade, aviation and shipping in the UK’s “net zero” goals. It would also meet XR’s demands for Citizen’s Assemblies to be set to give the public a greater say in how the country tackles the crisis.

Mother of two Miranda Irwin brought along her four-year-old daughter and six-year-old son – who doesn’t start school until Monday. “It’s too important to miss,” said the 35-year-old Londoner, who lost her job as a part-time teacher during the pandemic.

“We need to think of the next generation as well as the people round the world suffering from climate-related crises right now,” she added.

“People used to say, ‘You can’t stop flying, you can’t just stop doing things.’ But the pandemic has shown that we absolutely can stop doing things. And we should stop doing the most harmful and destructive things.”

Metropolitan Police limited the central London protest to the particular roads around Parliament Square between 9.30am and 7pm on Tuesday – and also told XR not to use boats, vehicles or other structures as part of their procession.

Met Commander Jane Connors warned that anyone taking part who knowingly fails to comply with the conditions in the days ahead “may be liable to arrest”.

Amelia Halls, a 22-year-old archaeology graduate from London, said she would keep coming back out to protest in the days ahead if the government failed to support Ms Lucas’ bill.

“The coronavirus is terrifying but so is the climate crisis,” she said. “We can’t wait for the virus to be over to act. Young people are here because we’re really, really scared about our future – and we need action now from the government.

Sit-ins are expected to be held around Parliament Square, outside City Hall in Cardiff and St Peter’s Square in Manchester for at least ten days.

“Rebels will choose to sit in the streets – overnight if necessary – to maintain a constant presence and pressure until our voices are truly heard,” XR organisers wrote in a Facebook post.

Clare Farrell, one of the founders of the movement, defended holding protests during a public health crisis, saying organisers had encouraged social distancing and the wearing of masks.

“Time doesn’t stop – we can’t let 2020 go by,” she said. “This is the ideal time to give the parliamentarians a message. It’s an emergency and we have push for change right now.”