This follows last week's fire at the Bank of Lisbon building, in which three firefighters died.
It also follows the recent fire at Brazil’s National Museum in Rio, which gutted 20 million items.
Egoli Heritage Foundation chairperson Herbert Prins said these fires again highlighted how political and official neglect and maintenance cut-backs were placing lives - and South Africa’s valuable heritage - at risk.
“Our foundation has previously expressed concern about the state-of-the-art gallery, which is home to one of the continent’s most valuable collections.
"In 2017, we were informed that JAG does not meet fire-safety requirements. In fact, neither structural engineers nor fire-safety inspectors wanted to sign off on the building following the disastrous attempts by the Johannesburg Development Agency to renovate the building,” said Prins.
He accused city authorities of playing with fire and putting the lives of their employees and visitors at risk.
“If lives are lost, the mayor will have blood on his hands,” he said.
In fact, in October 2016, city mayor Herman Mashaba publicly committed to the restoration of JAG as the epicentre of culture in Joburg.
"Two years later, nothing has been done," said Prins.
Many other heritage buildings in the city were similarly non-compliant with fire-safety regulations.
The problems at many state-owned heritage buildings are systemic, implicating public works departments at all three spheres of government, he added.
Other at-risk buildings include the Drill Hall, Marshall Street Barracks, the Rissik Street post office and the Turbine Hall - buildings of immense significance.
The foundation has called on local, provincial and national authorities to appoint a commission of inquiry to advise on how to deal with the problems that confront heritage structures and collections.