A Sydney activist has been released from hospital after sustaining injuries during a dramatic police arrest.

Danny Lim, who is widely recognised in Sydney for his sandwich board signs, was left bloodied after police tried to arrest him when he “failed to comply with a move on order”.

Video footage posted on social media shows officers trying to detain the 78-year-old man on Tuesday morning, in a shopping complex on George Street in Sydney.

During the attempted arrest Mr Lim appears to be forced to the ground, falling headfirst.

NSW Police said “an independent review has been launched, which will examine the actions of police during the incident”.