SYDNEY/WELLINGTON (Reuters) - Significant damage was reported along the western coast of Tonga's main island on Tuesday following the weekend's massive volcanic eruption and tsunami, but a closed airport and downed communications are hampering international relief efforts.

The New Zealand High Commission reported the damage along the western coast of the main island of Tongatapu, where there are many vacation resorts, and the waterfront of the capital, Nuku'alofa.

The South Pacific archipelago has remained largely cut off from the world since the eruption on the uninhabited volcanic island of Hunga-Tonga-Hunga-Ha'apai cut its main undersea communications cable.

A thick layer of ash blanketed the entire island, the High Commission said, adding it was working to establish communications with smaller islands "as a matter of priority."

British national Angela Glover, 50, was killed in the tsunami as she tried to rescue the dogs she looked after at a rescue shelter she had set up with her husband in the South Pacific archipelago, her brother said, the first known death from the disaster.

There are no official reports of injuries or deaths yet but internet and telephone communications are extremely limited and outlying coastal areas remain cut off.

"We don't have any further information that would suggest ... significant casualties, although, as you would appreciate, information is still relatively patchy," Australia's Minister for the Pacific Zed Seselja told Nine's Today show on Tuesday.

"The priority now will to be get supplies to Tonga, and the biggest constraint on that at the moment ... is the airport. There is still a significant amount of ash," he said.

The airport was now more likely to be open by Wednesday, he said.

The United Nations said a distress signal was detected in an isolated, low-lying Ha'apai islands group, adding it had particular concerns about Fonoi and Mango islands. According to the Tonga government, 36 people live on Mango and 69 on Fonoi.

A satellite image posted by the U.N. Office for the Coordination of Humanitarian Affairs (OCHA) indicated there was damage to scores of structures on Nomuka island.

"Further volcanic activity cannot be ruled out," OCHA said, reporting only minor injuries but emphasising that formal assessments, especially of the outer islands, had yet to be determined.

The Ha’atafu Beach Resort, on the Hihifo peninsula, 21 km (13 miles) west of the capital Nuku’alofa, was "completely wiped out", the owners said on Facebook (NASDAQ:FB).

HELP ON STANDBY

Australia and New Zealand sent surveillance flights onMonday to assess damage and Seselja said Australian police had reported significant damage along beaches with "houses thrown around".

Australia said navy vessel HMAS Adelaide was on standby to provide humanitarian aid and disaster relief support if requested by Tonga.

New Zealand said a Hercules C-130 aircraft was ready to fly to Tonga on Tuesday to deliver aid supplies as soon as it was safe to land on Tongatapu.

Tonga's deputy head of mission in Australia, Curtis Tu'ihalangingie, said Tonga was concerned that aid deliveries could spread COVID-19 to the COVID-free nation.

"We don't want to bring in another wave - a tsunami of COVID-19," Tu'ihalangingie told Reuters by telephone, urging the public to wait for a disaster relief fund to donate.

Any aid sent to Tonga would need to be quarantined, and it was likely no foreign personnel would be allowed to disembark aircraft, he said.

COMMS DOWN

The eruption of Hunga-Tonga-Hunga-Ha'apai volcano, which sits on the seismically active Pacific Ring of Fire, sent tsunami waves across the Pacific Ocean and was heard some 2,300 kms (1,430 miles) away in New Zealand.

The impact of the huge eruption was felt as far away as Fiji, New Zealand, the United States and Japan. Two people drowned off a beach in northern Peru due to high waves caused by the tsunami, while officials in Japan reported several evacuations.

The island of Hunga-Tonga-Hunga-Ha'apai all but disappeared following the blast, according to satellite images from around 12 hours later, making it difficult for volcanologists to monitor ongoing activity. Experts said the volcano, which last erupted in 2014, had been puffing away for about a month before Saturday's eruption.

The Red Cross said it was mobilising its network to respondto what it called the worst volcanic eruption the Pacific hasexperienced in decades.

Alexander Matheou, the Red Cross' Asia Pacific director, said water purification to remove ash contamination, providing shelter and reuniting families were the priorities.

Relief efforts have been hampered by a lack of communication. Samiuela Fonua, the chair of Tonga Cable, said there were two cuts in the undersea communications cable that would not be fixed until volcanic activity ceased, allowing repair crews access.

"The condition of the site is still pretty messy at the moment," Fonua told the Australian Broadcasting Corp.