Tonga Runway Cleared for Volcano Aid Flights

Tonga has removed a thick coat of ash from an international runway on Wednesday after days of painstaking effort, clearing the way for desperately needed emergency aid to arrive in the isolated and disaster-stricken nation.

UN crisis coordinator Jonathan Veitch told AFP the runway on the Pacific Kingdom's main island, once buried in five to 10 centimetres (two to four inches) of volcanic ash, was again operational.

It is "cleared but not in use yet," he said, adding that Tonga could receive much-stalled flights from Australia and New Zealand from Thursday.

Three people were killed when the Hunga Tonga-Hunga Ha'apai volcano exploded on Saturday, triggering tsunami waves that ripped down homes and caused widespread flooding.

The overwhelmed Tongan government has called the dual eruption-tsunami "an unprecedented disaster" and reported that waves as high as 15 metres (50 feet) destroyed almost every home on some outlying islands.

Virtually the entire population of 100,000 people has been affected, and initial assessments indicate an urgent need for drinking water.

When the underwater caldera exploded, it fired debris 30 kilometres (19 miles) into the air and deposited ash and acid rain across the kingdom of 170 islands -- poisoning water supplies.

"Water supplies across Tonga have been severely impacted by ashfall and saltwater from the tsunami," said Katie Greenwood of the International Federation of Red Cross and Red Crescent Societies.

She said there was a "mounting risk of diseases such as cholera and diarrhoea".