Police are now investigating after CCTV captured the brutal attack.

The video shows the passenger walking onto the bus before a young woman charges on behind her.

She then grabs the victim by the throat before hitting her in the face with a metal dog chain wrapped around her wrist.

CCTV footage shows the attacker, who is wearing a coat with a fur trim and carrying an Adidas backpack, marching off the bus with the chain dangling from her hand.