The U.S. Consulate in Melbourne told Australia's national broadcaster that it received one of the suspicious packages.
Authorities said Wednesday that they were investigating suspicious packages that had been sent to several consulates and embassies in Melbourne and Canberra, the capital.
Australian Federal Police gave few details, saying only that emergency units were responding to suspicious packages delivered to diplomatic addresses in the two cities.
Victoria State Emergency Services began reporting hazardous-materials alerts along major streets that are home to numerous foreign consulates in Melbourne, the country's second-largest city, beginning early Wednesday afternoon (Tuesday night ET).
U.S. diplomatic officials in Australia told ABC, Australia's national public broadcaster, that the U.S. Consulate in Melbourne was among the institutions that had received the packages but that the U.S. Embassy in Canberra wasn't.
"We handled the package according to our standard procedures and in close coordination with local authorities ... who are investigating the incident," a spokesman for the Melbourne consulate told the news service.
No further information was immediately available about Wednesday's reports, which came two days after a suspicious white powder was discovered in a package at the Argentine Consulate in Sydney, Australia's largest city.
Haz-mat crews tested the powder and found no poisons or toxins.