Pacific Islands prepare for the worst from cyclones

Two powerful cyclones bore down on three South Pacific island nations today, knocking down trees and power lines and forcing widespread evacuations.

Weakening Cyclone Nancy was causing damage in the southern Cook Islands while Cyclone Olaf continued to pose a critically dangerous situation for Samoa and American Samoa, the Australian-Pacific Centre for Emergency and Disaster Information (APCEDI) said.

The centre said Olaf was about 200km northwest of the Samoan island of Savai'i, which was beginning to feel the effects of the powerful cyclone, predicted to strengthen by the time it reaches land in six to 12 hours.

Nancy was today about 100km north-east of Rarotonga in the Cook Islands and had knocked down trees and cut power on its east side, while also damaging buildings on the resort island of Aitutaki.

Some tourists had been evacuated from Aitutaki's resorts and taken to Rarotonga, while some had opted to stay on the island, the centre said.

No injuries have been reported.

Aitutaki's Pearl Beach Hotel had already suffered serious damage from wind and tidal surges while the bridge to the Aitutaki Lagoon and Spa was down.

"In Rarotonga, we are experiencing strong winds, rain and also heavy seas, affecting the north-eastern side of the main island," the National Emergency Operations centre's Teroi John Tini told Radio New Zealand International (RNZI).

While Nancy was weakening it remained a strong category two cyclone and a hurricane warning was still in force for the nation's less-populated eastern islands, the centre said.

While the Cook Islands is likely to avoid a direct hit from Nancy, Samoa and American Samoa are not expected to be so lucky.

Olaf may may be upgraded from a category four to a category five super cyclone, with winds of more than 200km/h predicted.

Schools, offices and the airport near Samoa's capital Apia are closed and people have been evacuated from low-lying coastal areas.

"We're expecting there'll be very heavy seas so there is likely to be sea flooding in coastal areas and the damaging waves on top of that can be very destructive," Erik Brenstrum of the New Zealand MetService told RNZI.

- AAP