High or "king" tides will sweep onto Tuvalu, just 26 square kilometressquare miles) of land scattered over nine atolls, none of which rises more than 4.5 metres (15 feet) above sea level.

"We are not quite sure what will happen but we expect most of the areas will be flooded by the sea for an hour or so," Hilia Vavae of the Tuvalu Meteorological Office told AFP.

Tuvalu has long warned it is at risk from a rise in sea levels caused by global warming. During negotiations on the Kyoto Convention on global warming a decade ago, then prime minister Bikenibeu Paeniu warned "the world's first victims of climate change" would be the 11,500 Tuvaluans.

United Nations secretary-general Kofi Annan also referred to Tuvalu, 3,400 kilometres (2,100 miles) north east of Australia, saying there was "trouble in paradise".

Tuvalu tried unsuccessfully to convince Australia and New Zealand to provide a special immigration quota "should the high tides eventually make our home uninhabitable", in the words of former premier Ionatana Ionatana.

Current Prime Minister Saufatu Sopo'aga says his government is thinking of suing Australia and the United States for their carbon emissions.

But science is divided with a recent study showing sea levels are not rising. The theory is that the land is subsiding because of improper land use and population pressure.

Vavae, a meteorologist, says the real problem in working out what is happening is a lack of long-term data. Parts of Funafuti were sinking but there was not enough information to say why.

The 14-nation, Australian-funded South Pacific Sea Level and Climate Monitoring Project installed a sea-level gauge on Funafuti in 1993, operated by Australias National Tidal Facility (NTF).

Two years ago NTF said the gauge showed "no visual evidence of any acceleration in sea level trends".

It suggested that human activities on the islets, such as chopping down coconut trees and paving roads, had contributed to the subsidence.

Vavae said most homes in the capital atoll Funafuti, which consists of 30 islets populated by 4,000 people, would be flooded, along with her office and perhaps the airport.

At 4:40 pm (0440 GMT) Thursday the tide will peak at 3.07 metresfeet) above mean sea level and on Friday at 5:19 pm (0519 GMT) will reach 3.1 metres (10.2 feet).

Saturday will also see much higher tides and which in recent years have lasted until May, Vavae says.

However, she said local people were not afraid because they know the tide will go out again.

"They do not like the way the main road is blocked by the tides," she said.

Successive high tides have spoilt the fresh water reserves under the atoll and in a bid to beat the sea, people put extra manure into their often-ancient compost pits used to grow the root crop taro.

"It is very hard here," she said.

Tuvalu is the Polynesian or Ellice Island part of the former British colony of the Gilbert and Ellice Islands. The Micronesian part became Kiribati and both become independence in 1979.

TERRA.WIRE