Prosecutors are reviewing a decision not to bring criminal charges over the deaths of three soldiers who collapsed during an SAS training exercise.
A pre-inquest was told that the review, launched by the Crown Prosecution Service after an appeal by two of the soldiers' families, may delay a full inquest into the deaths of Edward Maher, Craig Roberts and James Dunsby.
The Army reservists died after taking part in a training exercise on Pen Y Fan in the Brecon Beacons in July last year.
An inquest into all three deaths was due to begin in Solihull, West Midlands, in October but may now be postponed until May next year.
Details of the appeal to the CPS by family members emerged during a hearing before the senior coroner for Birmingham and Solihull, Louise Hunt.
After consulting with lawyers acting for bereaved relatives, Ms Hunt said: "Two of the families have submitted appeals against the CPS decision.
"It is very clearly my view that we cannot conduct the inquest until those appeals have been concluded."
The full inquest is expected to hear from soldiers who were manning checkpoints at the time of the training exercise and other military personnel involved in its management.
Lance Corporal Roberts, 24, was pronounced dead on the mountainside, while Lance Corporal Maher and Corporal Dunsby, both 31, were taken to hospital.
L/Cpl Maher died three hours later in Merthyr Tydfil's Prince Charles Hospital, while Cpl Dunsby was transferred to the Queen Elizabeth Hospital in Birmingham, where he died on July 30.
A number of other soldiers taking part in the programme on July 13, when temperatures hit 29C (84F), also collapsed and needed medical attention.
The CPS announced its initial decision not to press charges for gross negligence manslaughter in July this year.
A large amount of detailed material, including reports provided by expert witnesses, was considered during the original review of the evidence, the CPS said.
L/Cpl Roberts was originally from Penrhyn Bay, near Llandudno, while Cpl Dunsby was from Bath. At the time of his death, the Ministry of Defence declined to give details of L/Cpl Maher's home town.