Passengers on a flight from Lismore to Sydney last Friday saw black smoke in the cabin, only to find that the source was a passenger's Apple iPhone 4, which had seemingly combusted mid flight.

The iPhone began glowing red and emitting dense smoke on flight ZL319 last week, according to Regional Express (REX).

The iPhone had to be extinguished by the cabin crew.

"In accordance with company standard safety procedures, the flight attendant carried out recovery actions immediately, and the red glow was extinguished successfully. All passengers and crew on-board were unharmed," REX said in a statement.

The incident has been referred to the Transport Safety Bureau and the Civil Aviation Safety Authority for investigation, with the iPhone handed over as part of the inquiry process.

ZDNet Australia contacted Apple for comment this morning, but no response had been received at the time of publication.

While the cause of the apparent combustion is still unclear, the Civil Aviation Safety Authority recently issued a warning over lithium batteries in-flight. The safety authority limits the carriage of batteries to two, with a requirement for them to be placed in separate bags to protect the terminals and the battery from short circuiting.