Bridgend MP and member of the Defence Select Committee Madeleine Moon has said questions will be asked following the death of a soldier in Brecon.
Josh Hoole, from Scotland, collapsed following an early morning training march on Tuesday - the hottest day of the year so far.
The Ministry of Defence said Mr Hoole was taking part in an eight-mile 'standard fitness test' along tarmacked roads which started and finished at infantry centre Dering Lines.
In 2013, Lance Corporal Edward Maher, Corporal James Dunsby and Lance Corporal Craig Roberts died in the Brecon Beacons on one of the hottest days of the year.
A coroner ruled that neglect was a contributing factor. The Ministry of Defence later said it was "truly sorry".
Calls have since been made by the Commons Defence Committee for The Ministry of Defence to be liable for prosecution for the deaths of armed forces personnel killed during training.
Ms Moon said her thoughts are with the family of Mr Hoole.
MP Johnny Mercer, a former Army officer, said the Defence Committee would look into the incident, which comes three months after it published a report calling for the MoD to be liable for prosecution for the deaths of armed forces personnel during training.
"No death in training is acceptable," he said. "The details of this incident are unclear, but given our recent (Defence Select Committee) inquiry into deaths in training, we will of course be looking closely at the circumstances surrounding this tragedy."
The committee found that, since the start of 2000, 135 military personnel had died while taking part in training and exercises - 89 from the Army, 24 from the Royal Navy and Royal Marines, and 22 from the RAF.