-We will need to be assured that Australia's national security is properly looked after in the sale," a spokesperson for the Minister for Defence Peter Reith told ZDNet.
Optus currently operates defence satellites on behalf of the Australian government, raising concerns about national security information, should the carrier be sold to SingTel, which is majority owned by the Singapore government.
Canberra first voiced concern in April that SingTel's bid would give a foreign government access to information relating to national security.
Australia has now revealed it could place conditions on the bid.
Australia's Department for Defence can ask for the Treasurer to place conditions on the sale or alternatively, the government could make changes to the Telecommunications Act, if needed.
-It's about defence concerns and what are the possible things we could look at if national security is in question," he said.
The Department for Defence, however, was not at liberty to reveal whether there were any concerns being raised over Australia's defence at present.
"The Treasurer won't comment on that," Reith's spokesman said.
