Officials have confirmed a body was left to decompose for four days in Sydney's Royal North Shore Hospital because a worker forgot about it and went home.

A hospital spokesman says a family had viewed the body in a room in the morgue complex at the hospital earlier this year.

But a worker responsible for returning the body to the morgue forgot to do so and went home.

The body was not discovered for four days.

The spokesman says the next-of-kin was told about the incident at the time.

He says "individual human error" was to blame and if correct procedures had been followed the incident would not have happened.

He says the worker involved has been counselled and policies have since been reviewed.

Earlier this month, security was upgraded at the morgue because of fears people could have accessed the area when doors were left unlocked.

The North Shore-Ryde Health Service said a security assessment of the morgue early this year did not identify any concerns.

The service's general manager, Sue Shilbury, said there were no cases where bodies had been collected inappropriately or without paperwork being completed.

But she said automatic locks were being put on the doors.

"There possibly has been an occasion when the doors have been left unlocked and the staff have been spoken to about that," she said at the time.

"We're all human and we make mistakes but we're moving to fit locks that don't rely on an individual make sure that the doors are shut and locked securely."

The state opposition's Health spokeswoman Jillian Skinner says the morgue is clearly not being run properly.

"This morgue is obviously dysfunctional," she said.

"With bodies being left and lost for four days it could not be described as anything else."