A machete-wielding 'mad man' has been arrested at Cardiff city centre ahead of a Justin Bieber concert.

The man was brandishing a knife during a confrontation with an Asian taxi driver as he allegedly shouted he would 'chop all Muslims up'.

An eye-witness, who helped restrain one of the men until police arrived, said he wielded his machete 'like a mad man' as he got out of a car.

The witness, who does not want to be named, said the man went into a rage. "I went over to help and he threatened me. He was saying 'Muslims are dirty, they are baby killers, they are bombers'. I went to him to calm him down. He said 'get away. I'll chop all you Muslims up.

"He was just a mad man. He was targeting Muslims. There was no reason to kick off. There were kids everywhere. It was chaotic. There were teenage girls shouting and screaming."

Police wrestled one of the men to the ground just 500 yards from the Principality Stadium as thousands of fans gathered in Cardiff city centre for the pop concert.

One witness told Mail Online: "I walked past as there was lots of screaming and shouting as the police were there. saw a guy get arrested and the police officer hold the knife - it was massive. It's terrifying to think something like this could happen with so many people in town."

A foot-long blade was discovered at the scene in Cardiff city centre. Two men are now in police custody.

Terrified fans who fled the queue at the Principality Stadium following the disturbance returned to the line ahead of Bieber's Purpose World tour which will see 40,000 fans fill the stadium.

The incident comes just weeks after a terrorist attack in Manchester at an Ariana Grande concert.

22 people were killed on 22 May after terrorist Salman Abedi detonated a home made bomb in the foyer of the Manchester Arena.

Grande said she was left ' broken' after the tragedy but vowed to return to the city to hold a benefit gig in honour of the victims.

Some of the world's biggest music stars joined with the people of Manchester in a display of defiance and unity at the One Love concert as more than 60,000 people filled the Old Trafford Cricket Ground.