Saturday marks one week since a massive underwater volcano erupted near the island nation of Tonga in the South Pacific.

Support from other countries is moving into full swing.

Australia and New Zealand have been delivering drinking water, communications equipment and other supplies since Thursday.

A Japanese Air Self-Defense Force aircraft arrived in Tonga with a load of drinking water on Saturday.

But local residents are concerned about damage to agriculture caused by volcanic ash, and power shortages.

World Health Organization staff member Setoya Yutaro told NHK from the Tongan capital of Nuku'alofa by telephone that the situation is calm but that ash is still falling.

Setoya said that 99 percent of the island is blanketed in ash, crops have been damaged and distribution has been brought to a standstill. He said supplies of food and water are running low. He said that other islands were running out of petroleum and may soon not be able to generate electricity.

Setoya also said many homes had been partly or completely destroyed. He said recovery from the disaster will take time and long-term support will be required.