Fiji Airways is limiting the weight of its ATR flights due to what it calls "the prevailing seasonal weather conditions in the South Pacific region".
In a statement, the airline said flights will operate with reduced seating capacities, and some guests and checked bags may not be accepted on services for which they hold bookings.
"Fiji Airways wishes to advise our valued guests that due to the prevailing seasonal weather conditions in the South Pacific region the National Airline is subject to payload limitations on its ATR services to Pacific Islands destinations," it said.
It said the changes will affect flights to Funafuti International Airport in Tuvalu, Port Vila in Vanuatu, and Vava'u and Fua'amotu international airports in Tonga.
The airline added excess baggage and prepaid additional bags are suspended on these flights until further notice, and cargo acceptance is restricted to essential medical and humanitarian supplies.
Fiji Airways said the situation is expected to persist into January, and flights can be changed to a later date free of charge.
"Whilst unfortunate and undesirable, this decision is made in the interest of the safety of our customers," the airloine said.
"Guests holding confirmed bookings who wish to change their flights to dates after 30th January 2024 may do so free of charge by contacting Fiji Airways Reservations.
"Fiji Airways wishes to apologise for any inconvenience caused and thanks our customers for their patience and understanding," it added.
One customer Mich McConell-Wilson said on Facebook: "Not happy at all about this!"
"I have been waiting for confirmation on my paid flight back to Port Vila for at least 2 weeks now! I was supposed to fly back to Vila today (Monday), but I guess I'm going to remain stuck in Nadi until Fiji Airways decides its okay for people to fly.
"I have have to say...this is not acceptable. Use bigger planes for goodness sake...people need to get to their destinations!"