He said Second-Lieutenant Clifton Lam Jia Hao, 20, died of heat stroke after he collapsed during a three-day jungle course in Brunei on Jun 11, while the cause of recruit Andrew Cheah Wei Siong's death is acute pneumonitis.

Mr Cheah, also 20, died after fainting during a 2 km walk on Pulau Tekong on Jun 10.

Mr Teo was responding to questions in Parliament from Nominated MP Siew Kum Hong, who had asked for the status of the inquiries by Mindef into the deaths of the two soldiers, and whether additional measures would be taken to prevent them.

He pointed out that neither case was linked to medical screening.

On 2LT Lam's death, he said the Higher Board of Inquiry (HBOI) has established that the trainee pilot may not have hydrated himself adequately the training.

The inquiry found that during the course, he was required to take care of himself but was given a safety briefing beforehand.

He had been given four litres of water and purification tables to purify stream or river water for drinking.

In the case of Mr Cheah, an autopsy found that he had an infection which typically displays symptoms including cough, phelgm, fever and breathing difficulties.

Mr Cheah felt breathless but had no other symptoms.

'In these circumstances it was difficult for his instructors or platoon mates or indeed Recruit Cheah himself to have known that the breathlessness was caused by acute pneumonitis and not simply fatigue,' said Mr Teo.

The instructor allowed Mr Cheah to continue with a walk around the stadium in Pulau Tekong camp and did not pull him out as he was able to converse clearly. Mr Teo said that in both cases there had been no lapses in the training safety system, negligence or foul play on the part of any personnel.

He assured the House that the safety of soldiers in training is taken 'very seriously'.

'They are our sons and daughters and every life is precious to us,' said Mr Teo.

Soldiers are well prepared for training and strenuous exercises by ensuring that they get sufficient rest and follow a proper hydration regime.

Attending medics are also on-site while commanders look out for soldiers who show signs that they are not feeling well.

Mr Teo also reiterated that all soldiers go through a detailed medical screening process before enlistment.

The two deaths also led Mindef to call an unprecedented three-day suspension of physical and endurance training activities, to ensure proper procedures were in place.

Investigations into the death of full-time national serviceman Joe Foo Wei Rong who died in Sept are still ongoing.