A judge ruled that Louis Bancoult could take his claim, that the government acted unlawfully in clearing inhabitants from the remote Chagos Islands, to the High Court.

The islands, just south of the equator in the Indian Ocean, were cleared in the late 1960s and early 1970s to make way for the construction of a US military base on the main island of Diego Garcia.

The families on the islands had lived there for five generations before Britain entered into an agreement with the Americans to build the base - subsequently used in the recent bombing of Iraq.

Some 3000 islanders - known as the Ilois - had to move to Mauritius or the Seychelles, more than 1,000 miles away, where many have struggled to make a living.

Lawyers for the legally-aided islanders claimed the authorities "rode roughshod" over their human rights and their rights as citizens of the UK and colonies.

The application for leave to seek judicial review was opposed by the UK Government and HM Commissioner for the British Indian Ocean Territory (BIOT), which was accused of enforcing the unlawful ban on behalf of the Foreign & Commonwealth Office.

The government argued the High Court in London had no jurisdiction to hear the case and it should go before a BIOT colonial court.

'United by sense of injustice'

But Wednesday, Mr Justice Scott Baker ruled: "I am satisfied the applicant has at the very least an arguable case on jurisdiction."

Outside the court, Mr Bancoult's solicitor, Richard Gifford, said: "This will be very good news for the community.

"The injustice has gone largely unrecognised in the world for a generation.

"The community is united by this sense of injustice."

The Ilois want to return to some of the outlying islands of the Chagos group, away from the army base.

After the judge's decision, a Foreign and Commonwealth Office spokesman said: "We have noted the conclusion of the hearing.

"We will be strongly resisting the substance of the claims."