Federal Liberal MP and former Army officer Andrew Hastie has joined Cory Bernardi in arguing female soldiers should not be allowed to fight on the frontline.

Mr Hastie, who served in the elite Special Air Service (SAS) for five years, conceded it was not a popular view but told Sky News the "fighting DNA of a close combat unit is best preserved when it's exclusively male".

The West Australian MP argued the selection courses for combat roles are rigorous, and the work "incredibly exacting", but emphasised this was his personal opinion.

His comments come after Senator Bernardi controversially claimed women serving in combat roles could be against Australia's national security interests.

"It's about blurring the lines between political correctness and sound tactics in the name of what I think is social justice," Senator Bernardi told Parliament.

Loading

The Australian Conservatives senator was slapped down by Liberal senator and former Brigadier Linda Reynolds, who labelled his comments "a complete and utter disgrace".

Defence Minister Marise Payne also took to social media to express her disappointment about Senator Bernardi's "ill-informed views".

Loading

The Defence Force opened up its most demanding and dangerous frontline jobs to female soldiers in 2013 and since then, about 30 women have joined combat roles in infantry units.

While pushing for greater diversity within the Australian Defence Force, the Chief of Army, Angus Campbell, has also been quick to counter claims about "women taking over the infantry".

In a letter to senior colleagues late last year, he pointed out that male recruits still outnumber females four to one, and that 96.6 per cent of the Army's infantry officers are men.

But Senator Bernardi is not backing down, arguing he is simply voicing the concerns of the men and women inside the Defence Force.