Qantas is cutting airfares on domestic flights despite sharply rising aviation fuel prices, as it seeks to boost bookings amid a broader decline in consumer sentiment.

Qantas will reduce domestic flights due to rising fuel costs and uncertainty linked to the Middle East war, as it warns of up to $800 million in additional fuel expenses.

All flights into and out of Fiji were cancelled or diverted on Tuesday as Tropical Cyclone Vaianu swept through parts of the South Pacific nation.

A Qantas passenger jet flying from Sydney to Dallas was forced to return to Australia due to a medical emergency onboard.

Airlines around the world are cutting flights and raising ticket prices as the escalating conflict in the Middle East drives jet fuel costs sharply higher and disrupts key air routes. Several major carriers have already adjusted schedules and fares, highlighting the growing impact of the crisis on the global aviation industry.

Airlines around the world are struggling to contain costs after jet fuel prices surged far faster than crude oil, forcing carriers to raise fares, add fuel surcharges and cut flight capacity.

A Qantas flight from Singapore scheduled to land in Melbourne on Wednesday morning was diverted to Adelaide due to a technical issue.

Thousands of travellers have had their plans disrupted after a fire forced the evacuation of the Qantas terminal at Melbourne Airport.

Australian airlines will ban the use of portable power banks on flights starting next month following several international incidents, including a mid-air fire on a Virgin Australia flight in July.