New Zealand officials warn that some South Pacific islands are facing crop failures during a regional drought.

Tokelau has followed in the footsteps of Tuvalu - declaring a state of emergency because of a chronic water shortage.

The NZ Foreign Minister, Murray McCully, says Tokelau, a New Zealand-administered territory of about 1,400 people, has less than a week's drinking water.

Much of Tuvalu is in the same predicament.

The shortage has been blamed on a lengthy drought caused by a La Nina weather pattern.

Meanwhile a New Zealand Air Force plane carrying containers of water and desalination units has arrived in Tuvalu.

Mr McCully said other South Pacific islands are also reporting water shortages.

He says New Zealand is undertaking a regional assessment amid fears the drought could lead to crop failures and food shortages.