The dismissive remark of a witness to last night's Leytonstone stabbings has been taken up by social media users as the perfect riposte to Islamist terrorism.

A video of the aftermath of the attack shows the knife-wielder pinned to the ground after being Tasered by police.

A bystander shouts to him: ""You ain't no Muslim, bruv."

The phrase is being widely shared on social media, with users saying that it both disowns the violence and sidelines the perpetrator.

The phrase became the top-trending hashtag on Twitter across the UK on Sunday morning, used by Muslims and non-Muslims alike.

An eyewitness to the knife attack was quoted as saying the attacker had screamed about Syria.

I just saw a lot of people running but I ignored it and kept walking to get my train, but suddenly what I saw I couldn't believe my eyes and what I saw was a guy with a knife," the Guardian quoted an eyewitness as saying.

"As he was coming out this is what he said: 'This is what happens when you f*** with mother Syria, all of your blood will be spilled.'"

One man had serious knife injuries that were not thought to be life-threatening and two other people had minor injuries, police said.