Helicopters have ferried scores of residents and tourists out of a small New Zealand town as others boarded naval ships, three days after the region was completely cut off by landslides following a major earthquake.

Prime Minister John Key pledged to push emergency laws through parliament if necessary to prop up businesses in Kaikoura, a seaside tourist town famed for its whale watching and seafood delicacies some 150 kilometres north of Christchurch.

"If we are helping pay the wages and we can get some of the tourists back... then we can get through the worst of it and get you out the other side," Mr Key told business leaders in Kaikoura after flying in by helicopter.

Mr Key also said he was considering "throwing some money" at an international online campaign to promote Kaikoura once road access had been restored to reassure tourists it was safe to visit as the peak summer season approached.

International tourists contributed $NZ14.5 billion ($AU13.6 billion) to the New Zealand economy in the year to March, the private-sector Tourism Industry Association (TIA) estimates, up 20 per cent on the previous year and overtaking the dairy industry as the country's biggest export earner.

Several ships were diverted from celebrations of the Royal New Zealand Navy's 75th anniversary to head to Kaikoura with supplies and emergency aid.

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Transport Minister Simon Bridges said officials were working night and day to clear an inland route.

Mr Key rang US President-elect Donald Trump on Wednesday, after missing his calls earlier in the week.

Mr Key said Mr Trump expressed sympathies over the earthquake and the pair discussed the economy and trade.

Reuters