The islands had been beset by drought conditions caused by one of the most severe La Nina weather patterns of the last 50 years, he said.
Many weather stations in the area were recording 35 per cent of normal autumn and winter rainfall, he said.
Long range forecasts predicted more of the same, with below average rainfall expected for both islands over the next three months, he said.
"I'm very concerned because the forecast is for the reemergence of La Nina. It is highly likely drastic action will be needed."
A Ministry of Foreign Affairs and Trade spokeswoman said officials were looking at options on how to assist Tokelau.
She said a further update on aid to the island community would be likely be issued within the next day.
There was no information available on potential New Zealand aid to Samoa.
A New Zealand Defence Force Hercules earlier this week arrived in Tuvalu to deliver Red Cross workers and supplies, including two desalination units, as well as water containers.
Foreign Minister Murray McCully said Wellington-based High Commissioner Gareth Smith and another Foreign Affairs Ministry staff member had also travelled to Tuvalu and would stay to see what other help was needed.
"New Zealand will be working with partners and other donors to consider the best medium- to-long-term response options," he said.
Being the lowest-lying populated island in the world, Tuvalu's population of 11,000 is beset with environmental problems.
Rising sea levels have threatened livelihoods and homes, while increased saline contamination threatens water supplies and crops.
Last month Pacific Islands Forum leaders called for the urgent provision of international funds to help small countries at risk from climate change, saying the issue was the "single greatest threat to the livelihoods, security and well-being of the peoples of the Pacific".
