Foreign Office barrister Andrew O’Connor said the government (HMG) remained committed to open justice.

However, he argued that if all the evidence surrounding the attack in Sousse of June 26, 2015, was made public, it could help the planning of future attacks.

Instead, he urged judge and coroner Nicholas Loraine-Smith to hear some of the sensitive evidence about the massacre in private.

A total of 38 holidaymakers were killed in the attack, all of whom were Tui customers and 30 of whom were British.

O’Connor said: “HMG is naturally committed to the principles of open justice [and] naturally expects that all of the inquest hearings should be public.

“Private hearings can and indeed should be heard where necessary in the interests of national security and in this context, the safety of British citizens at home and overseas.”

While the coroner agreed that the inquest should not impinge on security issues, barrister Andrew Ritchie QC, representing some of the victims’ families for solicitors Irwin Mitchell, argued “a full and fearless investigation” required a policy of openness.

“Particularly in this context where we have UK citizens travelling abroad and accepting risk, not only in Tunisia but around the world,” he added.

While Ritchie admitted some evidence may have to be heard in camera (privately) if national security is considered at risk, he expressed concerns that such a move could be used to censor his own line of questioning during the inquest. He was assured this would not be the case.

Ritchie has claimed at previous hearings that the government failed in its duty of care in not persuading tour operators to stop sending tourists to Tunisia following an attack on Tunis’s Bardo National Museum.

A Tui spokesperson said after the hearing: “The safety of our customers is of paramount importance to us. Like others, we want to understand the specific circumstances that led to this terrible incident.”

The inquest begins on January 16, 2017.