Inquests into "friendly fire" cases will never hear evidence in person from US military witnesses, the Ministry of Defence has disclosed.
One coroner said yesterday that he was "surprised and outraged" that Britain was not challenging a blanket ban by the US on providing witnesses.
"So much for the 'special relationship' between the US and UK governments," he added.
This anger, which is shared by other coroners, follows criticism of the MoD and its US counterpart by Andrew Walker, the coroner who found in March that L/Cpl Matty Hull, a Household Cavalryman, was unlawfully killed by US fighter pilots in Iraq in 2003.
Last week, three soldiers were killed in a similar incident after an American fighter accidentally dropped a bomb on them during heavy fighting in Afghanistan.
The absolute nature of the US ban was revealed in an unpublished letter from Desmond Bowen, policy director at the Ministry of Defence.
Mr Bowen said the MoD "would prefer not to make continued requests for witnesses from the US when the response is already a foregone conclusion".
In his letter, distributed to coroners by the Ministry of Justice, Mr Bowen explained: "The US have confirmed categorically that they will not provide witnesses to attend UK inquests in person. While coroners may continue to ask for US witnesses to attend inquests in the UK, they should be aware that there will in all cases be a refusal."
As an alternative, Mr Bowen says the MoD would be happy to consider any timely request for an appropriate British witness, "subject to the limitations of relevant experience, availability and any security considerations".
The US will continue to provide written reports to families, but these will be edited to remove classified information and the names of those involved. But coroners said that this would not be enough to satisfy the families of British troops killed in friendly fire incidents.
Mr Bowen outlined revised working arrangements where there was "US connection" in the deaths of British service personnel.
He explained that although the US would provide information to British military investigators, that information would have to be returned to the US authorities when the investigation was completed.
Coroners could subsequently request access to this material, but they should allow "some weeks" for the US to consider whether it could be released.
© Copyright of Telegraph Media Group Limited 2007.