A terminal at Melbourne Airport was evacuated on Friday night after a threat reportedly made against the airline Tigerair.
All outbound flights were grounded and incoming planes redirected to a different part of Terminal Four which is specifically for Tigerair, ABC News reported.
The terminal was declared safe eight hours later at about 5.00am local time on Saturday and the airport is now operating as normal, according to ABC News.
The Age reported that it was understood the threat was related to a plane that was on the runway and the surrounding area.
"The threat did not pertain to the terminal area," the newspaper quoted an airline spokesman as saying.
Three inbound Tigerair planes were evacuated on the runway and passengers were transferred to buses which took them to the terminal, said the report.
Tigerair Australia chief executive Rob Sharp in a statement said: "Tigerair takes all security-related alerts extremely seriously".
"All necessary steps were taken by the airline to quickly involve the relevant authorities and implement precautionary measures to ensure passenger safety."
Some passengers were stranded in planes at the tarmac. Scott Marquardt, who said he was on board a Tigerair flight from Brisbane that landed about midnight, tweeted saying that the crew had announced they would be on the tarmac for at least an hour, according to ABC News.
He also tweeted that passengers were told some planes were disembarking but "we'll be on ours for a lengthy amount of time".
ABC News reported that some Tigerair flights had been disrupted but all other operations were continuing as normal on Saturday. Passengers were urged to check their website for updates.