The teenager who inspired the climate change school strikes is due to join protesters in London as they enter a seventh day of demonstrations.
Greta Thunberg is expected to address Extinction Rebellion members on Easter Sunday ahead of meeting senior British politicians next week.
The 16-year-old Swedish activist has already met Pope Francis and spoken at the European Parliament.
On Bank Holiday Monday, they plan to hold a picnic on the Westway and peacefully block the road near Edgware Road underground station.
Metropolitan Police Commissioner Cressida Dick said the policing operation had been unlike any she had experienced in almost four decades of policing, with more than 750 peaceful activists arrested in less than a week.
Hundreds of officers from other forces have been drafted in to help quell the ongoing disruption.
Police have been trying to confine the protests to one site in London, at Marble Arch, but protesters have ignored the threat of arrest and continued to block roads across the capital.
Ms Dick said: “We have shown that we are strong, we are determined.
“I have never – I’ve been a police officer for 36 years – I have never known an operation, a single operation, in which over 700 people have been arrested.
“It shows we are determined and we will carry on.”
On Saturday afternoon the police managed to successfully clear demonstrators in the junction at Oxford Circus, which was reopened to traffic, while dozens of officers carried out arrests on Waterloo Bridge and slowly removed campaigners who had attached themselves to a truck acting as a stage.
Extinction Rebellion members showed no signs of voluntarily shifting under the hot sun over the Easter weekend, watched by tourists and families enjoying the end of the school holidays.
On Saturday night, candlelit vigils were held as campaigners sang.
The Commissioner said she was grateful for the help from “hundreds” of officers drafted in from “several” forces, including the neighbouring City of London.
She added that custody suites in London were “certainly very busy” but not yet full, amid reports from demonstrators that some people had been taken outside of the capital.
Ms Dick said she was “not embarrassed” about the length of time it is taking officers to clear the streets, defending their “determination and the resilience and the courage that they are showing in the face of quite a lot of difficulty”.
She predicted that large numbers of people would be “furious” if the demonstrations affect the London Marathon, which will take place next Sunday.
The Commissioner said she will be talking to the Government and criminal justice colleagues to see if changes to the police’s powers should be made to help officers deal with non-violent demonstrators when they are acting unlawfully.
“That is the dilemma and if our powers are insufficient, if we don’t have sufficient deterrents in the criminal justice system, then I will certainly be asking for changes.”
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.