More than 3500 people were evacuated to emergency shelters in Fiji as the biggest cyclone in 20 years swept across the Pacific island nation, just days after the storm killed four people and destroyed thousands of homes in nearby Samoa.

Tourist resorts on many of Fiji's islands have been evacuated and authorities warned people to remain in shelters yesterday as Tropical Cyclone Evan battered the country, blowing over trees and destroying houses.

Authorities said Cyclone Evan had generated destructive winds of up to 170mph.

Torrential rain was likely to lead to flooding as the storm passed the main islands of Vanua Levu and Viti Levu.

Fiji's weather bureau said Evan was rated a category four storm, the second highest level, and was moving only at about 18 kph (11 mph), meaning the destructive winds could last several hours.

Prime Minister Frank Bainimarama ordered public servants to stay at home and put emergency services on standby. Power supplies have been cut as a precaution against falling power lines, including in the main tourist town of Nadi. Airlines grounded flights to and from Fiji, stranding about 1900 visitors.

Australia and New Zealand offered support to Fiji ahead of the storm and have search and rescue personnel on standby.