A man affected by the Troubles in Northern Ireland claimed to be plotting to assassinate Queen Elizabeth on a trip to the US in the 1980s, an FBI document reveals.

Released on the FBI’s online vault, the document outlines what appears to be intelligence provided to federal agents about a threat to the Queen’s life in California 40 years ago.

The Queen and her husband, the Duke of Edinburgh, made an official visit to the west coast of America in February and March 1983.

The file states that a phone call was made by “a man who claimed that his daughter had been killed in Northern Ireland by a rubber bullet”.

It adds: “This man additionally claimed that he was going to attempt to harm Queen Elizabeth and would do this either by dropping some object off the Golden Gate Bridge onto the royal yacht Britannia when it sails underneath, or would attempt to kill Queen Elizabeth when she visited Yosemite National Park.”