The Australian government has increased its security alert level and has issued a general warning after receiving information about a possible threat to US or British interests in the country.
Attorney General Daryl Williams said the information is unsubstantiated and not specific to any particular location.
However, he added that it is sufficiently credible to be taken seriously.
He said all federal, state and territory law enforcement, security and intelligence agencies have been advised of the possible threat and are co-operating with their international counterparts to investigate the information and any unusual activity.
Williams gave no further details or any indication of the source of the information.