Police will today continue to investigate the deaths of two serviceman who died during a military training exercise on the hottest day of the year.
A third serviceman was last night in a serious condition in hospital.
The three were part of a group training in the Brecon Beacons, some of Wales’ most rugged terrain, on Saturday when temperatures topped 29.5C (85.1F).
Soaring temperatures may have been to blame for their deaths, military sources say.
The Ministry of Defence and police said they were both investigating the incidents, which happened near the Storey Arms Centre.
A spokesman said: “The MoD can confirm that it is working with Dyfed Powys Police to investigate an incident during a training exercise on the Brecon Beacons on Saturday in which two members of military personnel died.
“The two servicemen’s next of kin have been informed.”
The Brecon Beacons is one of several locations British military use as part of their training.
Its rugged and sprawling terrain helps prepare soldiers physically and mentally for warfare as well as put their logistic skills to the test, making it an ideal area for elite forces personnel like the SAS.
However the Beacons’ jagged topography can prove dangerous even to the most hardened and physically fit.
Earlier this year an army captain was found dead on a snow-covered Corn Du mountain. It was thought that Rob Carnegie had been taking part in a gruelling 17-40 mile march in freezing conditions in the Brecon Beacons as part of a selection process for the special forces regiment, when he collapsed and died.
However, this time investigators are examining whether hot temperatures played a major factor.
A source said: “It is a case of the people succumbing to being affected by the training that they were doing.”
Members of all four of South Wales’ mountain rescue teams said they had been called out to assist when the two servicemen died.
Thirty members of Central Beacons, Brecon, Western Beacons and Abergavenny-based Longtown Mountain Rescue Teams joined the operation near Pen y Fan, which is the highest mountain in south Wales.
Mark Moran, from Central Beacons MRT, paid tribute to its members who took part in the rescue operation.
“They are all volunteers, who are highly trained and dedicated” he said.
“We were working alongside military personnel who remained extremely calm and professional during this tragic incident.
“Our thoughts are now with the families of those involved.”