The University of NSW is warning students about a threat made against staff and students on an anonymous chat room.
The university took to its Facebook page to specify Kensington Campus, saying: "We are treating this incident seriously and have been liaising with the NSW Police through the anti-terrorism and security group and Local Area Command."
NSW Police Superintendent Gavin Dengate said the person who posted the threat purported to have a firearm.
"We initially take all threats seriously until otherwise proven," Dengate said.
"Certainly by [the police presence at the university]
we've taken it seriously but we've also taken a measured approach."
Dengate said there were uniformed and plain clothed police on campus and while classes were running as usual, the team was updating the university regularly.
"There have been other threats in relation to other issues also," Dengate said.
A university spokesman said no students would be penalised for leaving if they did not feel safe.