WELLINGTON, Feb. 15 (Xinhua) -- Cyclone Rene battered the main island of the south Pacific island nation of Tonga on Monday after earlier sweeping over islands in the north.

Wind gusts of up to 230 km per hour had been forecast for the southern part of the Ha'apai group and Tongatapu.

Police Commander Chris Kelley said the capital Nuku'alofa was battered by very strong winds and torrential rain for about 50 minutes. Trees have fallen across power lines and buildings have been damaged, Radio New Zealand reported.

Phone lines have gone dead late on Monday night. Evacuation plans were in place and people have boarded up their homes.

The Fiji Met Service said that Cyclone Rene is not expected to move away from Tongatapu until Tuesday morning.

So far, there were no reports of injures. People had been advised to seek higher ground.

Rene, which has been downgraded to a category three cyclone, is still forecast to carry sustained winds of 155 km an hour and momentary gusts as strong as 230 km.

The Tongan government has been encouraging people to gather in large public buildings for their safety.

Government departments, banks and most shops in the capital were shut.

New Zealand Prime Minister John Key told a press conference on Monday that the New Zealand government was monitoring the situation in Tonga closely.

A New Zealand Air Force Hercules left Whenuapai on Monday afternoon for the Cook Islands following Cyclone Pat last week.

It was carrying relief supplies including tarpaulins and tents, as well as Defence Force personnel who will help with the clean-up.

The South Pacific nation of Tonga has a population of 101,000.

New Zealand's National Institute of Water and Atmospheric Research (Niwa) said on Monday that it was still predicting near normal tropical cyclone activity across the southwest Pacific for the rest of the season through to April. On average, nine tropical cyclones occur in the region each cyclone season.

"Countries east of the date line, including Niue, Tonga, and the Southern Cook Islands are at higher risk than normal because of El Nino conditions. Parts of southwest French Polynesia ( Society and Austral Islands) can be affected by tropical cyclones during El Nino, so these islands should also remain vigilant," Niwa said in a statement.