Police have conducted mass counter terrorism raids across Melbourne.
Several arrests have been made in a joint operation involving hundreds of Australian Federal Police (AFP) agents and Victorian police officers.
"Victoria Police and AFP can confirm the execution of a number of search warrants across Melbourne early this morning as part of a joint counter terrorism operation," a Victoria Police spokeswoman said on Tuesday.
She said there had been a number of arrests but could not confirm the exact number.
It was understood the operation was ongoing.
Police have set up a crime scene at the corner of View and Glen streets, Glenroy, in Melbourne's north.
News Ltd said national security agencies had uncovered a plot by Islamic extremists to launch a suicide attack on an Australian army base, which was understood to be Holsworthy Barracks on Sydney's western outskirts.
It said the raids involved a suspected terrorist cell of Australian nationals of Somali and Lebanese backgrounds.
The Australian newspaper said members of the group had been observed carrying out surveillance at the army base and other suspicious activity around defence bases in Victoria.
It also said the cell had been inspired by the Somalia-based terrorist movement al-Shabaab, which had connections with al-Qaeda.
The investigation dubbed Operation Health, involving 150 members of the AFP, Victoria Police and ASIO, was launched in January, the paper said.
