It's feared up to 2500 buildings in NSW have highly flammable cladding installed similar to that being blamed for London's devastating tower block fire.
The aluminium cladding is suspected to have acted as an accelerant in the blaze that destroyed Grenfell Tower with at least 12 people confirmed dead and many more missing.
According to a report obtained by the state opposition under freedom of information laws in 2015, up to 2500 buildings were identified as using the non-compliant material, commonly known as Alucobest.
The NSW government says it began investigating the issue following the Lacrosse building fire in Melbourne's Docklands in 2014.
However, it still has no idea how many buildings are at risk.
Councils were warned of the dangers of non-compliant cladding on high-rise buildings in August 2015, Housing Minister Anthony Roberts said on Thursday.
The department also held seminars in October 2016, along with Fire and Rescue NSW, explaining the requirements of the National Construction Code and the enforcement powers available to them.
"The government takes the issue of fire safety in residential buildings very seriously," the minister told AAP in a statement.
"My agency will monitor the investigation into the London fire to determine whether there is any relationship with the combustible cladding matter and whether any further action should be taken on this matter in NSW and at the Commonwealth level".
Opposition regulation spokeswoman Yasmin Catley said the government response to the issue had been "negligent and lazy".
A spokesman for the Department of Planning and Environment has described the 1500 to 2500 figure in the 2015 report as a gross estimate, produced from development approval and Australian Bureau of Statistics data to indicate the potential of the problem.
"Neither of these data sets includes data on building materials used," he told AAP in a statement.
Non-compliant cladding does not mean a building is inherently unsafe, he added.
The NSW government last year announced it would improve building certification laws after a review found apartment fire safety practices were ineffective.
It proposed a string of reforms, including better annual checks for existing apartment buildings and more frequent inspections of large blocks during construction.
A City of Sydney spokeswoman said the council was not aware of any buildings in the city that had non-compliant cladding.
