Labour leader Phil Goff says reports a plane was diverted to New Plymouth solely to pick up Prime Minister John Key yesterday raised concerns about special treatment.
"We are talking about an election campaign and something being done to facilitate one particular group within that election campaign. If that was diverted solely for the Prime Minister and his party at the inconvenience and expense of other passengers, that would be quite wrong. It's not simply because of inconvenience to an individual that you would divert a flight."
He said he could not remember any other previous such incident at such a time.
"I want to know that this wasn't special treatment. That wouldn't be the New Zealand way, it wouldn't be acceptable."
He said Mr Key needed to provide an assurance that the diversion was not at his behest.
"The Prime Minister might think he owns Air NZ - he doesn't. We as New Zealanders own it - it's not a special or private tool for his own use or for him to sell."
He said if a steward had also endorsed Mr Key or asked for votes for him over the loudspeaker "that would be unfortunate as well" but he did not want to make a big deal of it.
But Mr Key said Mana candidate Sue Bradford needed to get a sense of humour after criticising him for taking the flight.
Ms Bradford said the diverted flight to collect Mr Key and take him to Auckland showed that Mr Key "has gone power crazy".
But Mr Key said there were other stranded passengers after his 845pm flight was cancelled, and he was making arrangements to stay in New Plymouth overnight when Air New Zealand called to tell him a plane had been diverted.
"There were a number of passengers that got on the plane, not just the people that were with me. That was all relatively standard.
"The air hostess in control of the cabin, I know her pretty well. I've had lots of flights with her. She was finishing her PA and I said to her, 'party vote National, party vote National', and she said over the PA, 'John wants you to vote for him'.
"If Sue Bradford doesn't like it, she needs to get a sense of humour.", He rejected that he had been given special treatment, though he could not remember it happening to him before.
"We were surprised when they rang. We didn't ask for it."
"Felt like special treatment"
Earlier today, a passenger on board the diverted flight said the move "felt like special treatment".
Mr Key has brushed off criticism of his flight last night from New Plymouth to Auckland, which saw a direct Nelson-Auckland flight diverted to collect him.
The prime minister did not ask for the flight to be diverted, and it was standard practice for Air NZ to divert flights to pick up stranded passengers, a spokeswoman said.
Flight passenger Lee Hesser, a US resident, this afternoon said Mr Key and three others had filled four of the seven empty seats on the plane during the unscheduled stop in New Plymouth.
At the end of the flight, she asked an attendant whether it had been diverted to pick up Mr Key.
The attendant replied: "Yup, pretty much".
"If it had been business as usual, would they have made an unscheduled stop in New Plymouth to pick up a few people? It just really felt like special treatment."
Ms Hesser said some passengers were upset by the delay.
Their annoyance was increased by an in-flight announcement where an attendant told passengers that Mr Key wanted them to vote National, she said.
"I have never been diverted for anything other than an emergency. It looked to me like this was political."
Air New Zealand said the diversion was made because a flight from New Plymouth to Auckland had been cancelled, leaving passengers including Mr Key stranded.
The cancelled flight was the last of the evening and there was no opportunity to transfer affected passengers to Auckland, it said.
"Air New Zealand does occasionally divert flights to pick up passengers from cancelled flights if there is limited or no opportunity to re accommodate those passengers onto other services directly from that airport."
Ms Bradford said the incident showed Mr Key "has gone power crazy".
"Out of the blue, passengers on that flight were advised that the plane was to be diverted to New Plymouth for 'operational' reasons.
"Little did they realise that 'operational' meant their flight was diverted simply to pick up the Prime Minister."
The flight was over half an hour late as a result, Ms Bradford said.
"On top of that, while in the air the stewardess announced that passengers should vote National, apparently at the request of John Key.
"This goes beyond the sort of born to rule arrogance that is normal with National.
"These are the actions of a man who has lost all perspective on how a Prime Minister should behave."
Meanwhile Air New Zealand said the in-flight announcement was a response to "light hearted banter" from Mr Key.
"While on their way to Auckland the flight attendant responded to some light hearted banter amongst the passengers and at the end of her PA announcement reminded everyone to vote on the weekend and mentioned John Key wanted her to vote for him."