The World Bank has estimated the damage bill from a volcanic eruption and subsequent tsunami which devastated much of Tonga a month ago will be more than $125 million. 

The eye-watering cost of recovery, the equivalent of nearly 20 per cent of Tonga's GDP, comes as new images from the Australian Defence Force (ADF) show personnel wading through rubble strewn across parts of Atata Island.

Hundreds of Australian soldiers have been helping the Pacific kingdom as part of Operation Tonga Assist 2022.

The World Bank's impact assessment report found 85 per cent of the country's population was affected by the unprecedented eruption that coated the archipelago in centimetres of volcanic ash and created waves strong enough to flatten islands. 

The county's international underwater fibre optic cable is still out of action and communications within Tonga remain strained, after the eruption broke the connection in two places.

The report found that while the volcanic ash fall and tsunami caused widespread devastation, the impact of each differed depending on the sector, the World Bank's liaison officer Natalie Latu told the ABC's Pacific Beat program.

"For instance in the agriculture sector, the volcanic impact was larger than the tsunami impact," Ms Latu said.

"Damage attributed to the volcanic impact was 80 per cent, whereas damage attributed to the tsunami was 20 per cent."

Eighty-five per cent of agricultural households across the country were affected, with crops, livestock and fisheries bearing the brunt of the disaster.

However, the tsunami brought the most damage to the tourism sector, destroying infrastructure such as resorts, public spaces and natural assets like waterfronts.

The World Bank's report said about 600 buildings across Tonga were damaged or destroyed by the tsunami.

Three hundred of these buildings were homes, and it is estimated 1,525 people from the Tongatapu and Ha'apai island groups have been displaced. 

The estimated damage bill does not include the "significant losses" associated with an economic loss of tourism, agriculture and infrastructure activities as a result of disaster recovery. 

Ms Latu said it was unclear how long the recovery would take.

"The Tongan community have been extremely resilient in clearing the debris, making their home safe, trying to get back to life as normal as it can be, and as soon as possible," Ms Latu said.

The World Bank's post-disaster damage assessment was conducted to help Tonga's government and its partners direct support for recovery, reconstruction and policy. 

Australia is one of several countries from across the region providing aid to Tonga.

"We have to date delivered 220 tonnes of relief supplies, they've principally come by air," ADF Lieutenant General Greg Bilton told the ABC.  

"We now have actually started proper clean-up operations on a number of islands."

Last week, China committed more than 100 trucks and excavators to help accelerate the recovery. 

"For years, China has provided assistance that meets the development needs of Pacific island countries including Tonga in line with the principle of sincerity, real results, amity and good faith," China's Foreign Affairs spokesman Wang Wenbin said.