The United States and Malaysia have offered logistical support to help get people out of Kaikoura.
During a news conference at Parliament this morning, Mr Key said about 140 people were on a priority list for transport out of Kaikoura today.
They would go on four New Zealand Defence Force (NZDF) NH90 helicopters from Woodbourne Airbase, near Blenheim.
American ship USS Sampson was here for the New Zealand Navy 75th anniversary celebrations this week, and Mr Key said the US had offered its two helicopters to help the evacuation effort.
"In addition to that, the Americans have a P3 Orion [aircraft] which they're going to add to our P3 Orion to undertake the aerial surveillance work, and the Malaysians have also offered a helicopter."
Finance Minister Bill English said it was too early to put figures on the repair and rebuild costs from Monday morning's 7.5 earthquake, but the biggest impact on the economy would be the damaged transport links.
The Picton and Wellington ports had "significant issues" from damage and disruption. These things were a pretty hard fix, he said.
The state highway north of Kaikoura, which is the main arterial route from the North to the South Island, would be significantly disrupted in parts for quite some time.
"The cost will fall to the government, quite a lot of it, but some will also fall to the relevant ports.
"The business that's most directly affected is KiwiRail... but that will just be part of a wider picture of disruption for a lot of businesses."
Mr English said while the Earthquake Commission's coffers were depleted after the Christchurch earthquakes, the commission had a government guarantee.
"So there's no question about their ability to extend their coverage and meet claims that are going to be made."
While most homes and buildings would have private insurance, the cost of rebuilding state highways rested solely with the government.
Acting Civil Defence Minister Gerry Brownlee said, beyond the immediate response, the government was considering what Kaikoura would look like in future.
"So here's a town that is largely dependent on a tourist market that has farming and fishing interests as well, so we're looking at how we maintain the activity that's there and support the people through what's a difficult time."
He said centres from Amberley to Wellington had sustained damage and would need government attention.
Mr Key questioned whether the parts of State Highway 1 damaged and covered with slips and rubble should be rebuilt as it was.
That part of the highway sustained major damage after the 7.6 earthquake early on Monday morning, with several slips and huge amounts of rubble covering parts of the road.
As well as the road, 14km of the rail line and six rail bridges were damaged.
Transport Minister Simon Bridges said it would take months to clear and repair that stretch of road, and the rail line alongside it, but he ruled out any change to the highway's location.
Economic Development Minister Steven Joyce would travel to Kaikoura to assess the best way to help local businesses through a support package.
Mr Key said the government did not yet have an idea of how much that would cost, or what structure it might take.
He said if people did not have insurance, the government would look at giving them some support.