Senator George Mitchell, former chairman of the Northern Ireland peace talks at Stormont, has made an unusual intervention in a long-running dispute between the owner of Harrods in London, Mr Mohamed Al Fayed, and the US security services over an alleged plot surrounding the death of Princess Diana.
In an unprecedented move Senator Mitchell is liaising between the Pentagon and Mr Al Fayed over top secret files held by the US Defence Intelligence Agency and the National Security Agency.
Mr Mitchell is proposing that Mr Robert Tyrer, a chief of staff in the US Defence Department, use his security clearance to review the files to see if there is any evidence that would help the French authorities investigating Princess Diana's death in a car crash in Paris two years ago.
Mr Tyrer would then report back to Mr Mitchell's office. He would not reveal the details of the papers but would disclose whether there were any references to a plot or whether such allegations are considered officially to be a fabrication.
The aim would be to end suspicions that have surrounded Princess Diana's death, including allegations by Mr Fayed that there had been a cover-up over the crash, which killed her, Mr Fayed's son Dodi and their driver.
Details of the proposals are contained in a letter from Mr Tyrer at the office of the secretary of defence at the Pentagon to Mr Mitchell. The letter follows a series of failed attempts to get the documents released under the US Freedom of Information Act following requests from Mr Fayed.
In the letter Mr Tyrer says: "I understand the complexities of the case and your concern that the reviewers may have missed information of relevance. I am willing to review the relevant documents myself after a thorough briefing on the case by you and your colleagues. I would then meet you to discuss my findings and determine what, if any, additional actions might be taken.
"I am hopeful that my proposal to personally review the relevant documents underscores our willingness to be responsive to the concerns you have raised."
Mr Fayed had pressed Mr Mitchell's office to act after failing to make progress. He is also suing an American lawyer and two former spies who asked for £20 million to pass on what are now known to be forged CIA documents detailing security service surveillance at the time of the crash.
In Mr Tyrer's letter he explains that the US information act has to be administered scrupulously, and documents are either declassified and released or kept secret under various acts of Congress.
US security agents were involved in a security alert on the day of Princess Diana's wedding to Prince Charles after a tip-off that a bomb had been mailed from the US as a present, papers released by the FBI have revealed.
There was another alert 10 years ago in New York when FBI agents photographed a Noraid demonstration, fearing that the princess could be a target of IRA terrorists.