Specialist police teams will be heading to London this weekend to help deal with two weeks of protests planned by Extinction Rebellion, the environmental activists who brought the capital to a standstill over Easter.

Metropolitan police will be put on 12-hour shifts from Monday, the first day of Extinction Rebellion’s action, to free up as many officers as possible from regular duties.

Forces across England have already been asked to contribute specialist “protest removal teams” trained and equipped to deal with protesters using locks and glue to hamper efforts their removal as they attempt to block key routes.

The Met was criticised by politicians this year after protesters used such tactics to block four key locations in central London, some for more than a week, to establish semi-permanent protest zones.

At a briefing at Scotland Yard on Wednesday, Nick Ephgrave, an assistant commissioner, said: “I think what we learned from Easter was that we need to be agile, we need to be probably slightly more proactive and more ready in anticipation of what we might expect. That was the lesson we learned from Easter … we need to react swiftly. We need to be as proactive as we reasonably can, on what we know, and be prepared to change and shift.

“And I think that agility is the thing that we learned, the need to be agile and the need to be able to respond quickly to develop these situations rather than allow them to develop and then try and deal with a much bigger issue later on.”

Ephgrave indicated that his officers could also take a different legal approach. Previously, officers using section 14 of the Public Order Act had to go through a lengthy process, before any arrest, of notifying protesters that they were in breach of an order, then giving the people time to decide whether they would comply with it.

“The legislation around public order is drafted in a different era,” he said. “And it’s not particularly helpful because it wasn’t really designed to deal with what we’re dealing with now.”

Extinction Rebellion is starting two weeks of protest action on Monday, occupying 12 sites in London. At similar mass demonstrations by the group in April about 1,100 people were arrested and the policing operation cost £16m.

Pointing out the pressures on the police, Ephgrave said his officers would also be dealing with about 30 other public events in the same period, including the state opening of parliament.

Officers have already been requisitioned from their regular duties for a total of 83,000 shifts to tackle protests so far this financial year, Ephgrave said. It was a drain on frontline resources on a greater scale than that caused by the London Bridge terror attack and Grenfell tragedy in 2017.

“There is a cost to all of this. There is a cost to communities in London, to your average Londoner,” he said. “There is a cost to our people, and there is a cost to business. It’s undoubtedly the case that we will not necessarily be able to deliver a service to the level we would want to, right across London, during this two-week period.”

An Extinction Rebellion spokesperson said: “We appeal to the humanity of the government and authorities to remember that we are non-violent protesters. We appeal to their humanity to remember that we are facing an unprecedented global emergency. Many are losing their lives already and we are called upon as human beings to act now.

“We also say to them, the people of London and every other person that we cannot do this without them. We invite them to join us, along with the doctors, teachers, scientists, the young and the old, on the streets from 7 October.”