A new geological study has shown that many low-lying Pacific islands are growing, not sinking.

The islands of Tuvalu, Kiribati and the Federated States of Micronesia are among those which have grown, because of coral debris and sediment.

One of the authors of the study, featured in the magazine the New Scientist, predicts that the islands will still be there in 100 years' time.

However he says it is not clear whether many of them will be inhabitable.

In recent times, the inhabitants of many low-lying Pacific islands have come to fear their homelands being wiped off the map because of rising sea levels.

But this study of 27 islands over the last 60 years suggests that most have remained stable, while some have actually grown.

Using historical photographs and satellite imaging, the geologists found that 80% of the islands had either remained the same or got larger - in some cases, dramatically so.

They say it is due to the build-up of coral debris and sediment, and to land reclamation.

Associate Professor Paul Kench of Auckland University, who took part in the study, published in the journal Global and Planetary Change, says the islands are not in immediate danger of extinction.

"That rather gloomy prognosis for these nations is incorrect," he said.