The Metropolitan Police has cleared the Special Air Service (SAS) of its alleged involvement in the death of Princess Diana saying that there is "no credible evidence" against it.

"The final conclusion is that whilst there is a possibility the alleged comments in relation to the SAS's involvement in the deaths may have been made, there is no credible evidence to support a theory that such claims had any basis in fact," the police said in a statement.

The police received some materials in August that indicated possible involvement of members of the SAS in the 31 August, 1997 car crash that killed the Princess of Wales and her partner, Dodi Fayed, in Paris.

"Whilst there is a possibility that the alleged comments in relation to the SAS's involvement in the death may have been made, there is no credible or relevant evidence to support a theory that such claims had any basis in fact," Metropolitan Police Assistant Commissioner Mark Rowley wrote in a letter to Sky News.

"Having reviewed the exercise and its findings, I am satisfied there is no evidential basis upon which therefore to reopen any criminal homicide investigation or refer the matter back to the coroner," he added.

The letter states that the police has informed the Royal household about the probe into SAS's role in Diana's death.

"In light of this information, I have today also written to the Royal House and Lord Justice Baker informing them of the above and providing a copy of the concluding summary."

A 2008 inquest into the death of Princess Diana found that she had been "unlawfully" killed. Her death was attributed to the "grossly negligent" driving of the Mercedes as well the paparazzi vehicles that were following her car when it crashed.