Mr Cuthbert and his friends Paul and Luke O'Shaughnessy, all from Manchester in the UK, and Alex Roberts, from Cronulla, were shaken after the incident but said they did not hesitate once they saw the incident unfolding.

"We all kind of chased, worked together, but it was Luke who was the real hero. He pursued him the hardest and managed to get a grip of him with another man," Mr Cuthbert said.

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"Luke is down at the police station giving a statement."

Mr Cuthbert said the alleged offender looked Caucasian, aged around "24 or 25", and had curly hair.

He would not comment on claims that the man was yelling Allahu Akhbar as he wielded the knife.

"He had blood on the knife and there was blood all over his clothing, so hopefully no-one was [badly] injured, fingers crossed it wasn’t serious."

Mr Cuthbert added that he had been living in Sydney for the past three years, and said he did not hesitate to chase the man because he sees Australia as his "new home".

"Me, Paul and Luke, we've adopted Australia as our new home and you hear about this happening all over, especially the UK, and you think coming to Australia you’re really safe and you feel like you've kind of got away from it.

"The first thing I'll do is give my mum a call."

Mr Roberts, who also gave chase to the alleged offender said the experience was frightening.

"We were all in the office and we saw the commotion downstairs and we all just legged it down and just chased. No…I didn't really think, I should have…"