Police are dragging away Extinction Rebellion protesters who have gathered near Parliament.
The demonstrators are practising "extended non-cooperation" to try and drain police resources, lying on the ground and waving flags with the XR logo.
Metropolitan Police officers have so far made 160 arrests for offences including breaching Public Order conditions, obstructing the highway, obstructing police and assault on an emergency worker.
Some protesters in the capital wanted to stop Prime Minister Boris Johnson getting to Parliament this morning.
The campaigners, who have also gathered in Manchester, are urging the government to prepare for a “climate crisis”.
XR plans to “peacefully disrupt the UK Parliament in London" for 10 days until MPs back the Climate and Ecological Emergency Bill.
Protesters have been told to “reconsider their actions” in Manchester following a rise in coronavirus cases.
City council deputy leader Nigel Murphy said: We are in the midst of a global public health crisis and we would ask demonstrators to seriously reconsider their actions at the current time.
"Manchester is currently under increased restrictions to limit the spread of the virus because the number of cases has been rising.
"Gatherings larger than six should only take place if everyone is exclusively from two households or support bubbles."
The Met said today’s protests could only take place off the main roads at Parliament Square Gardens between 8am and 7pm.
Commander Jane Connors confirmed: "The reason we have implemented these conditions is that we know these protests may result in serious disruption to local businesses, commuters and our communities and residents, which I will not tolerate."
One protester, Karen Wildin, 56, a tutor from Leicester, told ITV: “I’m here today because I have serious concerns about the future of the planet – we need to put this above anything else.
“Not a lot has been done on this issue, everyone needs to hear the message.”
Prominent XR member Sarah Lunnon added: “The failure to act on this issue will have a catastrophic impact on the future of us and the generations to come.
“We want to occupy Parliament Square to make our voices heard. Of course we’re in the middle of a pandemic but we’re balancing the risk, this is the biggest issue facing us.”