Ash cloaking a runway has hampered relief efforts to Tonga, as the scale of the damage from a volcanic eruption and a tsunami becomes clear.
New Zealand is trying to send clean drinking water and other supplies but planes cannot land at the main airport.
Some of Tonga's small outlying islands have suffered substantial damage, aid agencies say.
Two people have been reported dead, but with communications limited there are fears the true toll could be higher.
An underwater volcano erupted on Saturday, showering Tonga with ash and triggering a tsunami.