21/04/2017 1:18 PM AEST | Updated 21/04/2017 3:25 PM AEST

More Than 700 Patients' Private Medical Letters Found Dumped In Sydney Bin

NSW Health Minister Brad Hazzard has called for an external review.

Hundreds of NSW patients' private medical correspondence have been found dumped in a Sydney garbage bin.

Over 1,400 followup letters from specialists at outpatient and cancer clinics were found by a woman taking out the rubbish at an apartment block in Ashfield on April 11.

More than 700 public health patients at North Shore, Gosford and Dubbo Hospitals and hundreds more at six different private health providers have had their privacy compromised by the breach and had potential delays to their follow up medical care.

NSW Health has confirmed they are investigating the incident, which they say involved a subcontractor working for a company tasked with transcribing the medical letters, Global Transcription Services (GTS).

It is extremely distressing for cancer patients undergoing chemotherapy treatment to find out their personal medical details have been handled in this way."

According to GTS, the letters were dumped by a subcontractor while the company's manager was on leave in January.

NSW Health Minister Brad Hazzard said the subcontractor was experiencing health issues at the time which "affected her decision-making".

GTS has been asked to immediately cease printing and postal services for any NSW Health entity, NSW Health confirmed in a statement.

In a press conference on Friday, Hazzard said he was "very, very unhappy" about the "completely unacceptable" incident, and he had called for an external review into transcription services in NSW public health facilities.

"This is a human system and things can go wrong occasionally... but I want to be satisfied that we are doing everything possible to reduce the risk of human error," he said.

He also added that initial reviews suggest that no public patients have been put at risk by the failure to send the letters.

Fairfax Media / Nick Moir

"They have satisfied me at this point that patients are not at risk but certainly some have had a possibility -- only a possibility -- of their treatment being delayed," he told the media.

Eight patients at Dubbo Hospital have been identified as needing to have doctor's appointments or referrals brought forward.

The breach is the second report of NSW patients having private medical records compromised this year. In March, ABC News reported several incidents of privacy breaches at NSW hospitals, although they were not on the same scale as the latest incident.

Most of the letters were treatment progress reports from specialist consultations in December. The sub-contractor was supposed to take the letters home to post but instead stuffed them into the bin in Sydney's inner west.

Senior staff at NSW Health began an initial review of the letters on Good Friday, April 14.

"No evidence of a need for immediate clinical intervention or for individual patients to be contacted was found," their statement reads.

As of Thursday, all the mail had been sent on to the relevant addresses.

NSW Health has this week had preliminary discussions with consultants KPMG to conduct the external review of transcription services.

Opposition health spokesman Walt Secord labelled the breach "sloppy and dangerous".

"It is absolutely frightening that private medical records were left in rubbish bins in an Ashfield apartment block," he said.

"It is extremely distressing for cancer patients undergoing chemotherapy treatment to find out their personal medical details have been handled in this way."