The Metropolitan Police has said officers will be "more assertive" dealing with future protests by climate change activists Extinction Rebellion (XR), who last month staged demonstrations at a number of iconic London sites.

Cressida Dick, the Met's commissioner, told the London Assembly police and crime committee officers were unprepared for the "very new" type of protest, which saw thousands descend on the capital and occupy for 11 days some of the capital's busiest roads.

"Extinction Rebellion both came in larger numbers than we expected, used different tactics from what we had been led to believe and expected, and certainly new tactics well beyond anything that we had seen before," Ms Dick said.

She revealed officers made more than 1,200 arrests during the protests, which begun on 15 April at Oxford Circus, Marble Arch, Piccadilly Circus, Waterloo Bridge and Parliament Square.

“Next time we will have to quite simply have more people earlier, and be very very fast and assertive about getting people arrested and getting obstructions where we can lawfully out of the way quickly," Ms Dick added.

Asked about a small number of officers filmed dancing and skateboarding alongside demonstrators, Ms Dick said they were "not professional" and had gone "too far".

She also suggested Parliament should consider enacting tougher laws to deter similar mass peaceful protesters in future.

“I think a number of the people who were sitting there thinking, ‘This is OK’, would absolutely not think it’s OK if it was protests of a different political persuasion doing the same thing," Ms Dick said.

Extinction rebellion protesters explain why they glued themselves to Jeremy Corbyn's house

Susan Hall, a Conservative London Assembly member who sits on the committee, said she was "appalled" by the XR protests, which aimed to raise awareness of the escalating threat of runaway climate change.

Other Conservative and Brexit Alliance assembly members were also critical of XR and the Met's handling of the protesters, suggesting officers failed to end the demonstrations quickly enough.

But XR have promised to continue to launch non-violent demonstrations until the UK government meets its three demands.

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It is demanding the UK government declare a climate and ecological emergency, reduce greenhouse gas emissions to net zero by 2025, and create a so-called citizens’ assembly made up of members of the public, which would lead decision-making in the fight against climate and ecological breakdown.

Lorna Greenwood, a spokesperson fo XR, told The Independent: "Sadiq Khan wants 'business as usual' and now a London Assembly member says she was 'appalled' by the peaceful non-violent protests by Extinction Rebellion.

"We face a climate and ecological emergency and business as usual means disaster. What is really appalling here?