It has been revealed the husband of a woman found dead inside a freezer in a unit on Sydney's north shore flew out of Australia to China on Tuesday with their two young sons.

Key points: The body was discovered in a freezer on Wednesday morning

The body was discovered in a freezer on Wednesday morning The woman was a Chinese national and aged in her late 30s

The woman was a Chinese national and aged in her late 30s Detectives are in contact with Chinese authorities and are trying to confirm the two boys are safe

A police source close to the investigation told the ABC the body of the woman was found shoved inside a recently purchased industrial freezer, which was inside the Pymble apartment.

It is believed the body may have been there for several days.

Emergency services forced their way into the apartment complex at 10am on Wednesday, after concerns about the woman's welfare were raised.

It is understood the woman's husband and two sons, aged four and six, flew out of Sydney airport on Tuesday, after clearing Customs.

Police sources have also told the ABC that detectives have made contact with Chinese authorities but are still trying to establish the man's location, and confirm whether he has been detained by Chinese authorities.

They are also trying to confirm that the two boys are safe. It is believed they were both born in Australia.

Police say a post mortem examination will be conducted as soon as possible to establish how the woman died.

Forensics officers remained at the unit late on Wednesday night and have been taking statements from neighbours.

Neighbour Farrah Mahdavi said the incident was "shocking, unbelievable … because this is one of the best suburbs we've ever lived in".

"I'm so sorry for the family and for the children," she said.

"We are living in the 21st century, we're meant to be living a safer life."

The woman was already dead when police arrived at the apartment complex. ( ABC News: Mark Reddie )

The woman, a Chinese national aged in her late 30s, is yet to be formally identified.

Forensic officers have collected evidence and will determine how long the body was in the freezer for before being discovered.

The apartment the woman was found in is part of a large unit complex on Bobbin Head Road in the leafy suburb.