The US has blocked a court hearing on the detention of migrants in an overseas British territory, the BBC reported.

The supreme court of the Chagos Islands, known in the UK as the British Indian Ocean Territory, was due to hold a hearing this week on the detention of a group of migrants on the island of Diego Garcia.

The island is home to a military base which the UK leases to the US and, as a result, access is heavily restricted.

According to the BBC, the US government abruptly withdrew consent for journalists and lawyers representing the migrants to access the island, citing security concerns.

The US refused to provide those due to attend the hearing with transport, accommodation or food until its concerns had been addressed.

The court later issued an order vacating the hearing hours before it was due to begin. A hearing will now be held in the UK to determine how to proceed.

The case relates to around 60 Sri Lankans, including at least 16 children, who arrived on the island in 2021 and filed for asylum.

Most of the group remain there, housed in tents in an enclosed camp guarded by the private security company G4S.

UN representatives have previously said the situation amounts to arbitrary detention.

The Foreign Office has previously said it is “working tirelessly to process the migrants’ claims” and to find a suitable third country for those whose claims are upheld”.

Dispute with Mauritius 

The British Indian Ocean Territory, which has been British-owned since 1814, has been the subject of a decades-long dispute with Mauritius.

China-facing Mauritius, which won independence from the UK in 1968, maintains that the islands are its own and the UN’s top court has declared Britain’s ownership of the territory to be “unlawful” and called for it to be returned.

Britain’s stance on the territory has been coloured by the fact that it has leased use of Diego Garcia, the only inhabited island of the Chagos archipelago to the US.

Most personnel and resources on the island are under the Pentagon’s control, including most restaurants, shops, accommodation and transport facilities.

The US military, which has used the island as an important strategic base, including for bombing missions in the Middle East, claims the right to refuse access to areas operated or controlled by the Pentagon.

The BBC said that the specific security concerns being raised are not clear, but  reported they were understood to relate to a “site visit” due to be conducted as part of the legal hearing.