The severe drought in the tiny Pacific island nations of Tuvalu and Tokelau is "grim" and likely to get worse, the New Zealand Red Cross warned Tuesday.

Neither country had seen any significant rainfall for the last six months and none was expected for another two months, said New Zealand Red Cross international operations and emergency manager Andrew McKie.

The New Zealand Red Cross had sent two relief aid workers and supplies on Monday aboard a New Zealand Defence Force C-130 aircraft to work with the Tuvalu Red Cross and New Zealand government representatives and to assess any further assistance.

Both countries had declared states of emergency and water rationing had reached critical levels in Tuvalu and Tokelau, said McKie.

"We are working closely with Tuvalu Red Cross who asked for our assistance to support immediate impacts of the drought. As a result of this request we have mobilized 2,000 collapsible water containers, hand sanitizer, tarpaulins to be used to capture rain, two emergency desalination units and sent two New Zealand Red Cross aid workers."

The New Zealand Red Cross had identified the need for small emergency desalinators five years ago to suit the requirements of small isolated Pacific communities, sending units to Tonga and Vanuatu, he said.

The desalinators could convert sea water to drinking water at a rate of one to two liters per minute and were designed for emergency rather than long-term use.

Both units were being deployed to Tuvalu's small island group of Nukulaelae Tuesday, where it was reported just 60 liters of water was left for a population of 350.

New Zealand Foreign Minister Murray McCully said Monday that New Zealand would work with partners and other donors to consider the best medium-to-long-term response options to the crisis.

Tuvalu has a population of about 12,000 people, who live across nine atolls with a total land area of about 27 square kilometers.

Tokelau, which has a population of about 1,200, comprises three atolls located about 483 km north of Samoa. The atolls are 3 to 5 meters above sea level.