"But we remain confident from discussions (Earthquake Recovery Minister) Gerry Brownlee has had with reinsurers that they will come back.''
Reinsurers were looking for evidence that seismic activity in Christchurch was tailing off.
"The advice we see is it is slowing down'', said Mr Key.
"That's a really good sign, if we can carry on having less movement in Christchurch in time the insurance companies will come back and new players will come in - my understanding is there's been a lot of interest in AMI.''
Mr Key said that interest in AMI was coming from potential investors "right around the world''.
"That's why I'm not convinced that the insurance markets will close in New Zealand forever.''
The economic stimulus of the Christchurch rebuild is one of the factors Mr Key believes will help cushion New Zealand from the impact of the European debt crisis and prospect of double dip recessions in both Europe and the US.
"Whatever happens in the world we're going to spend $20 to $25 billion in Christchurch over the next five six or seven years.''