The US has blocked a British judge from holding a hearing on the British-held island of Diego Garcia to determine whether a group of asylum seekers is being unlawfully detained there. Around 60 Sri Lankan Tamil asylum seekers have been confined to a fenced camp the size of a football pitch on Diego Garcia for nearly three years after fleeing Sri Lanka and India by boat.  Diego Garcia hosts a large US-UK military base where the local commander of US forces on the island controls access to the facility. The Supreme Court of the British Indian Ocean Territory, which includes Diego Garcia,…