Foreign Minister Murray McCully says an acute shortage of fresh water has led to a state of emergency being declared in two tiny Pacific island states.
Mr McCully says there are reports of water shortages in other parts of the Pacific, which would harm crops and cause food shortages in the region.
"The situation is pretty serious," he said today.
The latest place to declare a state of emergency is Tokelau, a New Zealand territory of fewer than 1500 people on three coral atolls in the central Pacific.
On Monday, a New Zealand Air Force plane flew two desalination plants, emergency water containers and Red Cross workers to Tuvalu, after a state of emergency was declared last week in that country.
Some of Tuvalu's nine islands, which have a population of about 10,500 on a total of 26 square kilometres of land, are reportedly down to two days of supply of drinking water, Mr McCully said.
The capital, Funafuti, where most people live, has less than a week's supply.
Mr McCully told Radio New Zealand that regional weather patterns may mean quite low rainfall in parts of the Pacific for some months ahead.
He said the New Zealand government, which concentrates its international aid donations in the Pacific region, was trying to assess the situation to establish priorities.