President Baldwin Lonsdale said most houses in the capital Port Vila had been damaged or destroyed by Cyclone Pam, a category 5 storm.
"People are finding shelter where they can live for the night," he told the Thomson Reuters Foundation in Sendai, Japan, where he was attending a UN disaster recovery conference.
"The state of damage is still being assessed, we do not know exactly the extent of the damage...The number of casualties I do hope will be minor."
At least eight people have been confirmed dead but aid workers expect that number to rise sharply as more information becomes available.