Two British military officers have been acquitted over the deaths of three army reservists, including an Australian army soldier.

Two reservists died of heatstroke during a training exercise, and a third died in hospital weeks later of multiple organ failure after gruelling training tasks on the Brecon Beacons mountain range.

The men were carrying 25kg packs up the mountain range on one of the hottest days of the year.

The two men overseeing the exercise had the charges of negligence against them dismissed, the judge citing that they didn’t have training in heat illness and anyone in a similar position would have acted in the same way.