Soldiers may have been 'pushing themselves very hard'

Major Alan Davies told the BBC that the Brecon Beacons is one the most challenging terrains military personnel can encounter:

"On one end of the spectrum you have cadets being taken for mountain walking and at the other end of the spectrum the SAS use it," he said.

He added that the three men may have been carrying very heavy equipment and working to a deadline, which meant they would have been pushing themselves very hard.