Travel companies should display logos showing government travel advice for each area on their brochures.
The call comes from the coroner in the case of 30 British holidaymakers killed in the Sousse beach terrorist massacre in 2015.
The senior judge has raised concerns that holiday firms are still not doing enough to inform travellers about terror risks following the Tunisia killings.
Tui was criticised during the inquest, which took place earlier this year, for failing to give out enough information about the potential threat to tourists in the country two years ago, such as links to official government travel information and logos displaying travel advice.
In a newly-published report, Judge Nicholas Loraine-Smith said that the Thomson and First Choice parent company had “taken steps to change their website and promotional literature to make these logos and links more prominent” since the attack.
But he added that he was “concerned that other companies which sell holidays, or sell flights and hotel accommodation separately, may not have taken such steps, as a result of which members of the public receive insufficient information about the risks of terrorist attacks in destination countries”.
He also said he had heard evidence that before the attack travel companies did not have security advisors on their boards, and that while Tui now has such an adviser, he is “concerned that if other companies do not have similar security advisors at board level then hotels which they use will not be adequately protected.”
Loraine-Smith ruled in February that the 30 victims of the beach attack, later claimed by so-called Islamic State, had been unlawfully killed.
He mentioned Tui during his conclusion, finding that that despite the company’s responsibilty to inform the tourists of official travel advice, the only reference to it in their documentation was in relation to visas, which were not required for Tunisia.
A “crib sheet” used to help sales people answer questions on the deteriorating security situation in the country did not mention terrorism or where to find Foreign and Commonwealth Office Office travel advice.
However, he rejected a request by families to conclude that neglect by Tui or the owners of the Riu Imperial Marhaba Hotel, where the shooting took place, contributed to the deaths.
Mr Loraine-Smith wrote to the the secretary of state for transport, foreign and commonwealth affairs, Abta and the Civil Aviation Authority with his concerns.
An Abta spokesman said safety was “critical” to its members and told the Daily Telegraph: “Since the appalling attack in Sousse in 2015 there has been much greater public awareness of the global and indiscriminate nature of terrorist attacks and the role of travel advice is now more important than ever.
“Abta has taken steps that address the coroner’s recommendation for links to travel advice to be more prominently displayed.
“We have been working, and will continue to work, with our members to make sure that links to travel advice are visible on members’ websites and that customers are directed to travel advice before they book.”
A CAA spokesman said: “We can confirm we have received a report from His Honour Judge Loraine-Smith, following his inquests into the deaths of 30 British nationals in Sousse, Tunisia.
“We are now considering the report and will respond within the time permitted.”
An FCO spokesman said: “We will study the coroner’s report and recommendations and consider what actions we should take in response.
“The Sousse attack was the largest loss of British life to terrorism since 7/7, and devastated the lives of so many. Our deepest sympathy remains with all those people caught up in this horrific attack and we hope that the Inquest process has been of some help to the families.”
The trial has also started in Tunisia of 24 suspects in another case, the attack on the Bardo National Museum in Tunis, which took place three months before the Sousse assault.
Sally Adey, 57, from Shropshire, was among the 21 people killed.