Police have released footage showing the moment a 19-year-old bystander was “very seriously” injured when she was hit on the head with a gas canister and beaten to the ground during the Notting Hill Carnival.

Two groups of young men, mostly hooded, became involved a violent fight in Ladbroke Grove, west London, just after 7pm on Monday August 29.

The “completely innocent” teenager, who had been standing at the scene, was struck on the head with a gas canister and then kicked and punched.

The groups of men then fled in opposite directions, and the woman was admitted to hospital.

The footage was released by the Metropolitan Police on Saturday in a bid to persuade witnesses to come forward.

Detective Constable Sam Packer said: “The victim was left very seriously injured in hospital following this incident – although she has been discharged she continues to need treatment for the injuries she sustained.

“She is a completely innocent member of the public who was attacked without provocation or warning by people who were intent on causing violence.

“If you were there and saw what happened, or have footage that could help us identify those responsible, please do the right thing and contact us immediately.”