A passenger has described the moment people hit the roof of a plane travelling from Australia to New Zealand during what was described as a mid-air "technical event".

Brian Jokat said a number of people suffered head injuries after the LatAm Airlines jet dropped unexpectedly, throwing some out their seats.

Fifty were hurt and 12 were taken to hospital on landing in Auckland.

Emergency services said one was in a serious condition.

In total, New Zealand's St John ambulance service said it had "assessed and treated approximately" 50 patients who had been travelling on the Boeing 787 Dreamliner, which had taken off from Sydney.

Speaking to the BBC, Mr Jokat revealed that people had hit the ceiling with such force "some of the roof panels were broken" while others had been thrown down the aisles after the plane "dropped unlike anything" he had ever experienced before.

"There was blood coming from several people's heads and people were yelling and screaming and it was chaos," Mr Jokat added.

Another passenger told Radio New Zealand reported they saw people "flying around", leaving traces of their blood on the ceiling.

Some were not wearing their seatbelts, Radio New Zealand reported, quoting one of those on board.

Further details about the "technical event" or what caused it are still not known. FlightAware, an airline tracker, shows the plane losing altitude about two hours into the three hour flight between the two cities.

Latam Airlines said it "deeply" regretted "any inconvenience and discomfort this situation may have caused its passengers".

It said "a technical event during the flight" had "caused a strong movement" but provided no further information.

"The plane landed at Auckland Airport as scheduled," it added.

The aircraft was scheduled to fly on from Auckland to Santiago, the capital of Chile, where the South American carrier is based.

The flight has been cancelled and a new flight was scheduled for Tuesday, RNZ reported.