Tigerair Australia has joined its arch-rival, Jetstar, in cracking down on passengers who do not toe the line with its carry-on baggage rules.
Australia's second-largest budget airline will introduce stricter measures for carry-on baggage from September 18 after warning passengers for the past eight months about not exceeding its limits.
Tiger allows passengers to carry a maximum of two bags free of charge provided they do not have a combined weight of more than 10 kilograms.
Tiger commercial director Adam Rowe said the airline had been encouraging passengers to adhere to the baggage allowances since the start of the year by positioning extra staff at departure gates to issue warnings to people who exceeded the carry-on limits.
"From now on we are simply asking all passengers to play by the rules as there will be increased monitoring and the risk of a penalty charge for those that ignore them," he said.
"We urge passengers to make sure they book the right amount of baggage in advance of their journey at the time of booking, or after booking via manage my booking on our webpage, to avoid any extra fees at check in."
The airline will slug passengers $70 for carry-on baggage over 10 kilograms for a flight that is less than 1 hour and 45 minutes, or $85 for a longer flight.
Passengers will be forced to pay extra if the baggage exceeds 15 kilograms.
The airline will apply a discount of up to 40 per cent of the penalty on oversized baggage for the next three months, after which the full fees will apply.
Jetstar has also announced that it will position so-called "cabin baggage officers" at airports along the east coast to enforce its carry-on baggage rules.