Key Points:

Prime Minister John Key says it is "unacceptable" that both the Air Force's Boeing 757 passenger jets are being repaired in Alabama when they should be evacuating New Zealanders from Bangkok.

One of the aircraft is back in Alabama after returning home in August from a 16-month revamp.

The Air Force says it is now with Mobile Aeropace for routine "deep maintenance".

The other plane has been in Mobile for a year going through its revamp, and is expected back next month.

Mr Key said he learned both planes were "out of order" on Monday afternoon when going over evacuation plans with the Air Force.

It left him with no choice but to send the older, slower, smaller and more uncomfortable Hercules.

"I'm unhappy," he said. "We've got two 757s, neither of them are operable, neither of them have been operable for a considerable period of time, and we've got over 200 people in Thailand and I can't give them an adequate exit route."

When the 757 returned in August, Labour leader Phil Goff, who was then defence minister, said it would greatly enhance the Air Force's ability "to evacuate New Zealand citizens should the need arise".

Asked why repairs could not be done here by Air New Zealand engineers, Mr Key said: "You are asking the same questions I have today."

The two Boeing planes were bought in 2003 in a $221 million purchase and revamp project.