Extra police officers have been drafted in at some the main sites in London where climate change protesters are blocking traffic.
Dozens of officers formed cordons around the group on Waterloo Bridge while protesters reported that arrests were being made at Oxford Circus.
The Metropolitan Police Service has requested help from other forces to deal with the on-going disruption as the arrest total topped 700.
Some of the officers on duty on the bridge on Saturday were from the neighbouring City of London force.
Protesters also said that some of those detained had been sent as far away as Brighton and Southampton as the Met runs out of police cells in the capital.
Police have been trying to confine the protests to one site in London, at Marble Arch, but the protesters have ignored the threat of arrest and continued to block other sites, including Waterloo Bridge, Oxford Circus and Parliament Square.
The Met said people were only allowed to demonstrate at Marble Arch and anyone refusing to leave other protest sites would be arrested.
A spokesman said the force had “requested mutual aid” from other areas to help with the operation in London but would give no indication of numbers.
Despite the large police presence, the protests have remained peaceful, with demonstrators chanting “we love you” as officers advanced and surrounded a truck acting as a stage on Waterloo Bridge.
Protest organisers Extinction Rebellion (XR) also reported that after a flurry of activity in Oxford Circus, the police had “graciously withdrawn” and decided not to clear the area.
— Extinction Rebellion 🐝⌛️🦋 (@ExtinctionR) April 20, 2019
Greta Thunberg, the teenage founder of the school strikes against climate change is expected to address the protesters on Easter Sunday.
The 16-year-old Swedish activist is due to meet senior British politicians next week having already met with Pope Francis and addressed the EU Parliament.
Now awaits two days of train travel. Next stop London! pic.twitter.com/bzyx2EPdMK
— Greta Thunberg (@GretaThunberg) April 20, 2019
Activists who have set up a garden on Waterloo Bridge showed no signs of shifting under the hot sun, watched on by tourists and families enjoying the end of the school holiday.
Sites at Oxford Circus, Marble Arch and Parliament Square were also occupied, despite the removal by police of the pink boat which had acted as a natural focal point for the movement.
Police say more than 718 people have now been arrested, six days in to the XR protests, and 28 people have been charged.
With the pink boat no longer at Oxford Circus, supporters sat down in a circle at the centre of the junction.
The vessel has been replaced by two demonstrators holding a sign “We are the boat” after it was removed by police on Friday after five days.
Earlier on Saturday, about 50 police officers surrounded the group who said they had been told they could remain until “no later than 10.30am”.
One demonstrator said: “Holding the space is important and being arrested is not undignified.
“We are here for an important reason, so we should be prepared to be removed for that. Being arrested is a statement.”
It comes as a video of police officers dragging demonstrators along the ground by the arms on Friday emerged, after Home Secretary Sajid Javid urged police to use the “full force of the law”.
In the footage, a woman is seen being dragged along the road close to Oxford Circus by a police officer who then stumbles and falls over, knocking his hat off.
Another officer is seen dragging a man sideways.
It is one of the more aggressive encounters between police and demonstrators, which have so far remained largely good natured and peaceful.
Update: statement from XR:
“We would like to remind those who have ordered the police to use the “full force of the law” that #ExtinctionRebellion is peaceful and non violent.
We face a climate and ecological emergency. Now is not the time to be on the wrong side of history”
— Extinction Rebellion 🐝⌛️🦋 (@ExtinctionR) April 19, 2019
XR tweeted that the movement was “peaceful and non violent”, adding: “We face a climate and ecological emergency. Now is not the time to be on the wrong side of history”.
The group has pledged to continue causing disruption until its demands are met.
It wants the Government to declare a climate emergency and take action to reduce greenhouse gas emissions to net zero by 2025.