Cyclone Yasa has flattened homes, damaged roads and brought down power lines in Fiji - with authorities estimating it's caused hundreds of millions of dollars in damages.

Thousands of people sheltering in over 450 evacuation centres around the country.

Council for international development Aaron Davy told Heather Du Plessis Allan the best thing people can do is send cash.

"If people support organisations through providing funds, they can make sure New Zealand expertise can support Fijian authorities in the right way."

Davy says the sheer volume of 20 to 40 foot containers filled with public goods can stop vital supplies coming through, and undermine local businesses already struggling.

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