Photo: Tonga Geological Services

New Zealand and Australia have sent military surveillance flights to assess the damage a huge undersea volcanic eruption caused in Tonga.

Communications with the Pacific island nation remain limited since Saturday's eruption.

Residents who got messages out to the world described a moonscape left by tsunami waves and volcanic ash fall.

The single underwater cable that provides internet and international phone service was likely severed by the eruption.

The ash was contaminating drinking water, and New Zealand is planning to fly water and other supplies to Tonga on Tuesday.