Video on social media emerged showing the man lying motionless on the ground while an officer covers him with a taser.

A British Transport Police spokesman said: “A man has been arrested outside HSBC bank near Birmingham New Street station at 13.15 today.

“Officers were initially responding to a call regarding a concern for welfare outside the station, when a man was seen with a knife, he was subsequently arrested on possession of bladed article and has been taken to hospital,” he said, according to the Daily Star.

"The incident is believed to be drug related.”

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