A 30-year-old man has died resisting arrest after escaping a hospital where he was being treated for mental illness.

Police were called to Carillon Ave, Newtown, in Sydney’s inner-west about 1.30pm on Sunday when the man fled a nearby hospital.

He was being held under the Mental Health Act, NSW Police said in a statement.

“The man resisted arrest and collapsed at the scene before being taken to hospital, where he later died,” the statement said.

Seven Network reports an officer used capsicum spray and taser on the man in an attempt to control him.

A witness said she saw 15 officers “on top of him” during the arrest.

Newtown: The actions of police will be investigated after a man died following a dramatic arrest on Carillon Avenue. He was a mental health patient who had escaped from RPA Hospital. A female officer tasered him before back-up descended in numbers. @freya_cole #auspol #7News pic.twitter.com/yndjqJLaAe

— 7NEWS Sydney (@7NewsSydney) February 18, 2018

“My gut feeling was that maybe they used a bit of excessive force trying to arrest him,” she told the Seven Network.

“He looked like he may have been a big man but still, and they pulled him back up which made it even worse.”

The incident has sparked a police internal investigation, which will be independently reviewed.

A report will be prepared for the coroner.