Serial protester Danny Lim in hospital after ‘discontinued’ arrest in Sydney CBD

Serial protester Danny Lim has been left bloodied and seeking hospital treatment after a "discontinued" arrest by New South Wales police officers in the Sydney CBD on Tuesday.

Known for the sandwich boards he is commonly seen wearing, Lim was walking through the Queen Victoria Building while wearing a sign when security told him to leave. They called police, who then confronted him.

Speaking to Guardian Australia from hospital - where he was being assessed for a possible broken cheek bone - the 78-year-old claimed police "smashed me on the concrete floor", causing his cheek to bleed.

"I could be dead when they threw me down like that," he said.

A video taken by a witness showed Lim being pushed down by two police officers before being handcuffed while on the ground.

When he is picked up off the tiled floor, there is blood on the ground and on his cheek.

"I couldn't believe it," Lim said.

"I told them I suffer from PTSD.

"I couldn't believe Australia could do this."

Lim said an ambulance was called after more officers arrived and he was then taken to St Vincent's hospital.

He remained at the hospital on Tuesday afternoon while his facial injuries were examined.

Lim's face and sign were left bloodied and his hands and knuckles bruised.

Police confirmed they were investigating the incident. A spokesperson said footage from body-worn cameras was being examined.

The spokesperson said police were called to the QVB at about 11am, after receiving reports Lim would not leave the building after being asked to do so.

"Police will allege the man was subsequently issued with a move on direction by officers and failed to comply," the police spokesperson said.

"The man's arrest was discontinued after he struggled with police and sustained an injury to his cheekbone.

"He was treated at the scene by NSW Ambulance paramedics and taken to St Vincent's hospital."

The incident comes after Lim was arrested in early 2019 by police in Barangaroo for wearing the same sign that said "SMILE CVN'T! WHY CVN'T?".

After being fined $500 for offensive behaviour, the Sydney magistrate Jacqueline Milledge, who was critical of the responding officers' behaviour, ruled the signs might be cheeky but they were not criminally offensive.

Police handcuffed Lim in front of a shocked crowd after a phone complaint.