WELLINGTON: A search was underway Saturday for a ferry with 50 people on board that has not been seen for more than a week in the tiny island nation of Kiribati in the central Pacific.

New Zealand search officials, who have been called in to assist Fijian authorities, said the inter-island ferry MV Butiraoi was reported missing late Friday.

The 17.5-metre wooden catamaran left Nonouti Island for Betio Tarawa in the Kiribati Islands on January 18.

The 260-kilometre voyage was expected to take two days.

"We understand the vessel underwent repairs to its propeller shaft just before it departed," New Zealand Rescue Co-Ordination Centre officer John Ashby said.

"This may have contributed to problems navigating the journey.

"The weather in that part of the Pacific is currently moderate with some swells."

A New Zealand Air Force Orion plane has been dispatched to conduct an aerial search of the route the vessel was scheduled to take.

Kiribati a nation of 33 atolls and reefs with a total population of about 110,000, lies some 3,460 kilometres (2,150 miles) northeast of Fiji.