WELLINGTON (Reuters) - A drought-stricken Pacific island nation is down to its last few days of water, prompting a mercy dash by New Zealand and Australia with water-making equipment.

Tuvalu, the world's fourth-smallest nation sitting just below the Equator, has declared a state of emergency and is rationing water.

Tuvalu has a collective land mass of just 25 sq km (10 square miles) with its highest point five meters above sea level and is one of the countries most vulnerable to climate change and rising oceans.

Air force planes from New Zealand and Australia were combining on Friday to move a large desalination plant to Tuvalu, a group of small islands around 3,180 km (2,000 miles) northeast of New Zealand.

"The advice is that more capacity is needed to relieve the acute water shortage and replenish stocks," said New Zealand Foreign Minister Murray McCully in a statement.

"The large army desalination equipment...will help ease the critical shortage and should provide a sufficient buffer if the dry period continues as expected."

Residents in the capital Funafuti have been rationed to two buckets of fresh water a day. The country has a population of fewer than 11,000 on nine low lying atolls.

Emergency water supplies have also been shipped to the Tokelau island group, where 1,300 people are down to a few days water because of drought.

Rain, which supplies much of the water for the two nations, has been well below average for the past six months because of a severe La Nina weather pattern.

That has increased the strength of eastern trade winds across the Pacific, pushing rainfall to the west and away from the islands.

(Writing by Gyles Beckford; Editing by Nick Macfie)

Mochila insert follows.