An email from DFAT sent to Australians registered as being in Vanuatu and seen by AAP urged those outside Port Vila to await the availability of commercial flight departures.

The magnitude 7.3 earthquake, which struck Port Vila on Tuesday killing at least 16 people and injuring at least 200, caused massive damage to the city and surrounding areas.

The number of deaths and injuries is expected to rise as search and rescue operations continue.

A potential health crisis also looms as aid workers believe about 20,000 people on the island cannot access clean water.

Vanuatu-based UNICEF water, sanitation and hygiene specialist Brecht Mommen warned illness would likely spread.

“It’s a rush against time to get water trucks organised for those areas so that we prevent a second disaster, which is a diarrhoea outbreak,” he said.

The extent of damage to Port Vila’s water infrastructure remains unclear, with repair timelines uncertain.

Aid agencies have also noted challenges around official casualty numbers as they believe not all have been transported to hospitals and some injured residents remain trapped or are avoiding the severely damaged Vila Central Hospital, the main medical facility.

About 1000 people are estimated to have been displaced, according to the United Nations.

Relief efforts face significant challenges due to blocked roads, traffic congestion and limited communication networks.

President Nikenike Vurobaravu urged people to take care in areas hit by landslides and warned of “cascading hazards” following forecast heavy rain.

“Make sure your family is safe [and] help each other during this hard time for the nation,” he said in an address on the national broadcaster’s Facebook page.

Forecast rain could worsen landslides triggered by the earthquake, including a major slip that has blocked Vanuatu’s main seaport.

While humanitarian flights continued, local media reported Port Vila airport was expected to reopen for commercial operations on Sunday.

AAP