Metropolitan Police chief Cressida Dick says the force has been "stretched" by Extinction Rebellion protests, impeding its ability to respond to other crimes.

At the end of a week of demonstrations that has seen more than 1,100 arrests, the force was also dealing with the fatal stabbings of two teenagers in the city within a matter of hours.

Dame Cressida told the PA news agency she hoped the protesters would choose to either "protest lawfully" or "go home" after their "failure to take and occupy the streets that they wanted to".

She said: "If they do that then of course I can deploy many of my officers back to the streets, back to the neighbourhoods, back to the schools, back to the wards of the people of London.

"We are responding to all serious matters and urgent matters of course, carrying on with our crime investigations in homicide or armed robbery... but we're having to move work from one unit to another and the less urgent, less critical, less important work of course gets delayed."

Activists blocked the entrance to the BBC's central London headquarters on Friday, with some scaling the front of the building.

BBC staff members reported being unable to get in to New Broadcasting House on Friday morning as dozens of protesters camped outside the main entrance with banners urging the corporation to end its "silence" on climate change.

On Thursday, demonstrations focused on London City Airport, where protesters attempted a "Hong Kong-style occupation" of the terminal building, with hundreds blocking the main entrance.

One demonstrator, Paralympic cyclist James Brown, climbed on top of a British Airways jet, prompting criticism from Dame Cressida, who described the act as "reckless, stupid and dangerous".

On the same day as the airport protests, a 15-year-old boy was stabbed to death in Stratford, east London, and an 18-year-old man also died after suffering stab wounds in Camberwell, south London.

The incidents took the city's homicide tally to 114 in 2019 so far.

"It takes its toll on my officers too," Dame Cressida said of the mass demonstrations.

"I would like Extinction Rebellion to protest lawfully or go home and that would make it easier for everybody in the Met to provide the service we want to provide to Londoners."