by Barnaby Mason BBC diplomatic correspondent

A High Court ruling will be made on Thursday on the compensation claims brought against the British government by several thousand Indian Ocean islanders.

They were removed from their homes in the Chagos archipelago more than 30 years ago to make way for an American military base on Diego Garcia.

Most now live in poverty on Mauritius, but the judge's ruling is not expected to be the end of the story.

The islanders, who all hold British passports, were exiled in the 1970s

The Chagos islanders won a notable victory in November 2000. The High Court ruled then that the 1971 order excluding them from the British Indian Ocean Territory was unlawful and should be quashed.

The Foreign Office accepted the ruling, but has questioned how practical it would be for the islanders to return.

It has also fought their legal claims for compensation and resettlement.

'Shabby'

The new High Court ruling will decide whether the claims are in principle valid and can be argued in detail.

The judge (Duncan Ouseley) will not rule on the amounts of any compensation.

According to the islanders' lawyers, he will decide first whether the British Government was responsible in law for the physical removal of the islanders.

Then, assuming that it was, whether any or all of the claims should be struck out - disallowed - on the grounds that they are too old or that the claimants received what the government says was final compensation in 1982.

Behind these intricate legal arguments lies a shabby story of people evicted from their tropical island home in the interests of big power military strategy.

The naval and air base on Diego Garcia, where most of the islanders used to live, has become even more important to the United States since President Bush proclaimed his war on terror.

And the British Government is caught between its responsibilities to the Chagos islanders and its treaty obligations to Washington.