The hashtag #YouAintNoMuslimBruv has exploded on Twitter after a passer-by shouted the remark at a knife-wielding man who injured three people in a London Underground station.

A man, believed to be aged 29, threatened bystanders with a knife at the Leytonstone Underground station, about 10 kilometres east of central London.

The man was arrested after police used a Taser to subdue him, and is being questioned by police.

British police are treating the attack as a terrorist incident, with reports that the assailant screamed “this is for Syria” during the event.

Dramatic footage of the attack emerged on social media, showing the suspect remonstrating with people before swinging at one of them.

But it is the footage of the man’s eventual arrest that has gone viral on social media, thanks to what has been described as the “quintessentially London” response of a bystander.

As police handcuff the man and warn lingering bystanders away, one man can be heard shouting: “You ain’t no Muslim bruv! You’re no Muslim bruv! You ain’t no Muslim!”