The two soldiers who died during a training exercise in the Brecon Beacons were serving with the Territorial Army, according to the BBC.
Defence sources suggested the personnel had "succumbed" to unusually hot weather conditions during the drills in Wales.
The TA is a British volunteer reserve force which recently announced plans to increase its manpower to 30,000.
Army reservists are to get military pensions and healthcare benefits in a bid to drive up numbers, Defence Secretary Philip Hammon announced to MPs today. The new benefits are designed to drive up numbers from 20,000 to 30,000 by 2018 and also include the following:
- Smaller firms that employ part-time soldiers will receive an extra £500 per month when they are away on deployment.
- Companies that discriminate against staff who wish to sign up as a reservist will be more open to action at employment tribunals.
- Ministers have not ruled out legislating to ensure it is not a disadvantage when applying for jobs.
General Sir Peter Wall, head of the British Army, has welcomed the reforms to the Territorial Army and attempted to play down fears over the impact they could have on businesses.
Former head of the Irish Guards Colonel Ben Farrell told ITV's Daybreak that although the idea of boosting the number of reservists to 30,000 was "on the face of it a good idea", he was concerned by the "practicalities" of the proposal.
Chief of the General Staff Gen Wall said the Army had "very positive" talks with the Confederation of British Industry and small businesses over the potential impact they could face if an employee gets deployed.
Gen Wall added that the Army would look at "ex-regulars" and people inspired by today's reforms to help make-up the extra 10,000 reservists they aim to have before 2018.
Former head of the Irish Guards Colonel Ben Farrell told ITV's Daybreak that although the government's plan to boost the Territorial Army to 30,000 was "on the face of it a good idea", he was concerned by the "practicalities" of the proposal.
Colonel Farrell said he thought increasing the number of reservists from 19,000 to 30,000 by 2018 would be difficult to achieve and feared that businesses could be impacted if employees were called up on duty.
He added that he was less concerned over the Territorial Army's input on operations, pointing out that they had previously "done brilliantly overseas" and would be subjected to training before being deployed.
Employers will be encouraged to sign a voluntary charter guaranteeing that they will not stand in the way of employees who wish to be reservists, the Independent reports.
The newspaper also reports that they will receive an "enhanced compensation package" for staff who are away on duty, which could be as much as one in every five years.
The Treasury reportedly blocked an earlier plan to give employers tax breaks, as is the case in some other countries.
Some Army reservists will become specialists in areas such as cyber security, chemical and biological warfare and intelligence under plans to be outlined today, according to the Independent.
The newspaper reports that reservists will be able to take "enhanced training programmes" in these emerging areas as "an incentive to join and stay in the force".
It also reports that military planner believe that people who work in other professions - particularly in computing, sciences and languages - may already have skills that would be of use in these cutting-edge fields.
The white paper measures being unveiled by the Defence Secretary today are expected to make it easier for Army reservists to balance their military duties with their normal jobs.
Their current conditions are as follows:
- Expected to commit to between 19 and 27 days a year
- Paid around £35 for each day
- Expected to attend training in their own free time
- Entitled to a tax-free "bounty" of up to £2,100 for meeting time quota
The Defence Secretary will today announce a raft of changes to the role of the Territorial Army including possible rewards for companies who support reservists in their employment.
Philip Hammond is expected to announce a sharp rise in the number of reservists from around 19,000 to 30,000 by 2018, parallel with a reduction in the numbers of regular soldiers.
The Territorial Army will be renamed the Army Reserve and is likely to be given a special £42 million equipment budget.
Training will also be boosted, with more exercises held overseas, and smaller firms given financial incentives to let staff join up.
Reservists will get £40 million of new kit and extra overseas training opportunities in the latest steps to increase the size of the part-time forces.
Members of the Territorial Army - to be renamed the Army Reserve under the shake-up - will be able to use high-tech equipment including helmet-mounted night vision and upgraded SA80 rifles.
A white paper on Wednesday will set out financial incentives for small firms employing reservists.
It will set out how the number of trained reservists will increase from 19,000 to 30,000 by 2018 in preparation for them taking on more operations alongside their Regular counterparts.