Air Mauritius flight MK943 turned back while over Mount Gambier, South Australia, after a passenger made a bomb threat to crew, it is reported.
A man was detained by federal police after the Airbus A380 touched down safely.
An Air Mauritius spokesman has confirmed that a suspicious item was discovered on board.
Emergency crews were called to the airport at 2.38pm Melbourne time after the pilot radioed an alert.
A Melbourne Airport spokeswoman told reporters that there was “no danger posed to people within the terminals or wider airport precinct”.