A critical incident team will investigate the death of a 30-year-old man who collapsed as police attempted to arrest him in Sydney's inner-west on Sunday afternoon.

Police said they attended Carillon Avenue, Newtown, at about 1.30pm after the man fled a nearby hospital, where he was being held under the Mental Health Act.

Officers from the Inner West police area command found him and attempted to arrest the man.

However, he resisted arrest and collapsed at the scene before being taken to hospital, where he later died.

A police spokeswoman could not confirm whether or not a taser was used on the man.

A critical incident team will investigate all the circumstances surrounding the incident, and the investigation will be subject to independent review, police said.

A report will be prepared for the Coroner.