Pret A Manger should take action to prevent future deaths following the inquest of teenager Natasha Ednan-Laperouse, a coroner has said.
The 15-year-old suffered a severe allergic reaction after unknowingly eating sesame contained in an artichoke, olive and tapenade baguette she had bought from a branch in Heathrow Airport.
She died of anaphylaxis after collapsing on board a flight to Nice on July 17 2016.
Natasha’s father Nadim said she died because of "inadequate food labelling laws" and joined the rest of her family, from Fulham, south-west London, in calling for a change in the law to save lives.
Pret announced last week it will include full ingredient labelling on all of its products and the Government said it is considering a law change.
In a report published on Tuesday, coroner Dr Sean Cummings outlined "matters of concern" identified in Natasha’s inquest and wrote: "In my opinion there is a risk that future deaths could occur unless action is taken."
He said allergens were not "labelled adequately or clearly" on Pret packaging when products were prepared in their kitchens for direct sale under regulation 5 of the Food Information Regulations.
The rule allows for businesses to avoid full labelling requirements on food made in "local kitchens" but makes no distinction between small sandwich shops and large chains such as Pret.
"I was left with the impression that the 'local kitchens' were in fact a device to evade the spirit of the regulation,” Dr Cummings wrote in his report.
He also said there had been "no coherent or co-ordinated system for monitoring customer allergic reactions" despite more than 200 million items sold a year, adding the current system "remains highly inadequate".
"In my view, sales of 200 million items some with expressly commissioned but hidden allergens require a robust safety auditing system. The previous system was unsafe and the system proposed equally so in my view," he said.
The coroner also highlighted concerns over the "inadequate" length of epipens and dose of adrenaline, the combination of which “raises serious safety concerns”.
Dr Cummings said Pret chief executive Clive Schlee, Environment Secretary Michael Gove, the Medical and Healthcare products Regulatory Agency and the chief executive of Pfizer have the power to take action.
They must respond to the report by December 3 2018 with details of any action taken.
In a statement, Pret said it has always complied with relevant regulations.
"Following the coroner’s conclusion at the inquest, we announced last week that we are moving to full labelling of all products produced in our kitchens as quickly as possible, with immediate measures in the meantime," it said.
"We have also committed to improving our monitoring and complaints handling procedures to ensure allergy-related incidents are immediately escalated and reported on within 24 hours.
"We will be working with others, including the government, regulatory authorities, charity groups and industry peers, to secure legislative changes to better-protect people with allergies and deliver what the Ednan-Laperouse family have called for."
It comes after the family of a second person thought to have suffered a fatal allergic reaction to a Pret A Manger sandwich demanded answers.