A major manhunt has been launched in London after a man was stabbed on a busy train.

Disturbing video footage shared on social media showed a man in a hood wielding a knife while lunging at a person in a seat. Other passengers are seen shouting just a few rows away as the attack plays out.

Services between Shortlands and Victoria via Herne Hill were suspended on Wednesday amid a large police response.

Police said one man was left seriously injured with stab wounds following the assault, which took place shortly after two men boarded the train at Shortlands railway station.

No arrests have been made, and officers have said they are making urgent efforts to trace the suspect.