SYDNEY (AFP) - Soaring cabin temperatures meant 50 passengers and crew had to be treated for heat stress on Monday on a Qantas domestic flight in Australia, after a problem with the air-conditioning.

The flight was heading from Sydney to the Australian island of Lord Howe, a journey of around two hours, but was forced to turn back.

"QantasLink flight QF2260 travelling from Sydney to Lord Howe returned to Sydney due to a technical issue with the air-conditioning system," a Qantas spokesman said in a statement.

"Passengers and crew are being treated for heat exposure at the airport and two passengers were taken to hospital."

Paramedics were called to Sydney Airport to meet the flight and assess around 50 passengers and crew for dehydration, the New South Wales Ambulance Service said.

"That's what we were called for, reports that passengers on the flight had suffered from a high heat for a sustained period of time," a spokesman told AFP.

He was unable to confirm how high the temperatures were or how long the passengers were exposed to the heat.

"We assessed all the passengers and crew who came off the flight. Of those passengers, two people needed transport for dehydration, both adult females."

Reports said that the cabin temperature climbed to almost 40 deg C onboard the Dash-8 aircraft.

QantasLink operates flights to more than 50 city and regional destinations across Australia and Papua New Guinea.