In July, Foreign Office Minister Lord Howell had indicated that the opposite could be the case.
During a Lords debate he was asked whether the government would deny permission for Diego Garcia to be used for logistical support if the US backed Israel during military action.
Lord Howell replied: “The answer is obvious. If Israel was to take military action, the United States would be involved and if the United States was involved, we would be involved.
"This would be a triggering of global action and Diego Garcia would therefore obviously be dragged into it.”
The Guardian claimed a British military delegation flew to Tampa, Florida, to discuss contingency plans with US counterparts during the summer.