UPDATE 2pm: Parts of Curtin University were evacuated for about two hours earlier today after staff found two bottles containing a potentially explosive chemical with labels dating back to 1973.
The police bomb squad was called to remove the volatile gel, a derivative of TNT, which was found in a storeroom in the biomedical sciences building during a clean-up.
About 500 staff and students from several buildings were evacuated and a 300m exclusion zone was set up.
Department of Fire and Emergency Services incident controller Brad Miles said police bomb squad officers removed the two bottles, each containing about 100g of trinitrobenzelsulfonic acid – a derivative of TNT - in a blast bag and destroyed it.
"There was a medium risk of explosion," he said.
"Potentially I don’t think it would have been a big explosion, but still harmful to anyone in the immediate area."
Curtin University spokesman Ian Callahan said the chemical was no longer used in its laboratories and because of the potential risk, emergency services were asked to dispose of it.
"It is a substance that has a protocol in disposing of it so we sought expert advice," Mr Callahan said.
Mr Callahan said an internal inquiry would be done into why and when the chemical was used in the laboratories and why it was still being stored on site.