SYDNEY, Jan 13 (Reuters) - Relief agencies were sending aid to Tonga on Monday amid reports of extensive damage to low-lying islands in the South Pacific archipelago after they were battered by a strong cyclone at the weekend.
Early reports from emergency workers suggested that category five Cyclone Ian and its associated hurricane-force winds had caused significant damage to islands in the north.
Tonga's director of emergencies, Leveni Aho, said there was no communication with 80 percent of the worst-hit Ha'apai island group, including Lifuka, which bore the brunt of the storm.
About 8,000 people live in the Ha'apai islands, which are about 2,630 km (1,630 miles) northeast of the New Zealand capital, Wellington.
"The picture comes to hand now, it was really bad," Aho told Australian Broadcasting Corp. (ABC) Radio.
The governor of Ha'apai, Tu'i Ha'angana, said the damage was so bad he could see from one side of the island to the other, the ABC reported.
Two Tongan navy patrol boats were on their way to the Ha'apai Islands group with emergency shelter supplies and road clearing equipment. The Red Cross has sent a chartered flight with health, power and telecommunications experts.
The United Nation's Office for the Coordination of Humanitarian Affairs said a mapping specialist was due to arrive in the islands on Monday to assess its response.
There are five stages of tropical storm, with Typhoon Haiyan, which killed more than 4,000 people and caused widespread destruction in the Philippines in November, rated at five, the most powerful. Category four is defined by wind gusts of 252 kph (156 mph) or greater.
Cyclone Christine ripped across Australia's northwest earlier this month, battering coastal regions and closing major iron ore shipping terminals.
(Reporting by Jane Wardell; Editing by Paul Tait)