GENEVA - The United Nations reports emergency teams are on standby to provide humanitarian assistance to thousands of victims of a volcanic eruption and tsunami on the South Pacific island of Tonga.

Planes carrying humanitarian aid are unable to land in Tonga until the island's main runway is cleared of a thick coating of ash from Saturday's undersea volcanic eruption.

While a planned large-scale humanitarian operation is put on hold, U.N. officials say the government and local aid agencies are assessing the scale of damage and subsequent needs.

They say the Tonga government confirms two people have been killed and 150 houses have been damaged and destroyed on the main island of Tongatapu.

Jens Laerke is spokesman for the U.N. Office for the Coordination of Humanitarian Affairs. He says the latest reports indicate the country's capital, Nuku'alofa, has sustained a lot of infrastructure damage.

He says there is much concern over the well-being of people on two-small low-lying islands, who so far have not been reached.

"Clean water sources are another concern for the Tongan government who have issued advice requesting that people only drink bottled water, as water sources may be contaminated from the ash, debris, and sea water,' said Laerke. ' Assessments by the Tongan authorities are ongoing and should provide a better estimate of what is required."

The World Health Organization reports 89 displaced people are sheltering in evacuation centers on the island. Others rendered homeless by the disaster are staying with relatives and friends.

WHO spokesman Christian Lindemeier says the tsunami did extensive damage to the country's telecommunications infrastructure, including the undersea internet cable.

However, he says the island's medical warehouses and health facilities are undamaged, fully functional, and able to treat people with health problems stemming from this calamitous event.

"The concern, of course, is the around two centimeters of ash and dust that has fallen on Tongatapu, raising concerns of air pollution, potential contamination of water supplies ...To avoid the consequences of ash remain indoors and use masks when going out and drink bottled water,' said Lindemeier.

The WHO warns further volcanic activity cannot be ruled out, and urges people to stay alert and seek higher ground if tsunami alerts are issued.

Tonga is a COVID-free zone and has very strict protocols to preserve that status. U.N. officials note one of the first rules of humanitarian action is to do no more harm. They say they will make sure that all necessary protocols for entry into the country are followed.