Video report by ITV News Correspondent Emily Morgan
A second customer died from from an allergic reaction to an ingredient in a sandwich bought from Pret A Manger, the firm has confirmed.
The patron died after eating a “super-veg rainbow flatbread” that was supposed to be dairy-free.
The chain said it had been mis-sold a guaranteed dairy-free yoghurt, produced by vegan brand CoYo, that was found to contain dairy protein.
However, CoYo have said the claims are "unfounded".
Pret is already facing scrutiny over the death of 15-year-old Natasha Ednan-Laperouse, who was allergic to sesame and died after eating one of its baguettes.
Her parents have said they are “incredibly saddened” by the death of a second customer.
Natasha’s parents, Nadim and Tanya Ednan-Laperouse, have been campaigning for allergy awareness and a change into food labelling laws.
“We were incredibly saddened to learn of someone else losing their life from allergens in their food,” they said in a statement through lawyers Leigh Day.
“Our hearts go out to the bereaved family.”
The second customer, who has not been named, collapsed and died on December 27 last year after buying the sandwich in a store in Stall Street, Bath.
CoYo, a coconut milk brand that has been endorsed by TV cook Nigella Lawson, recalled its yoghurts in February after dairy traces were found.
Pret on Saturday said CoYo “mis-sold to Pret a guaranteed dairy-free yoghurt that was found to contain dairy protein”.
“This is believed to have resulted in the tragic death of a customer from an allergic reaction in December 2017,” a spokesman said.
CoYo responded in a statement which read: "The dairy-free product we provided to Pret in December 2017, at the time of this tragedy, is not linked to the product we recalled in February 2018.
"The product recalled in 2018 was made with a contaminated raw material that was only supplied to us in January 2018.
"Pret’s inability to provide us with a batch code, despite several requests, has severely limited our ability to investigate this further".
Bath’s council alerted Pret to the incident and the chain said it then withdrew all affected products.
Pret maintain that CoYo's dairy-free yoghurt "contained traces of dairy protein".
The chain said it had ended its contract with CoYo and is taking legal action.
The Food Standards Agency investigated along with Bexley council in London, where CoYo is based, before it issued an allergy alert.
CoYo is yet to comment on the death, but announced in February it was “devastated” to discover dairy in its yoghurts “especially as being dairy-free sits at the heart of everything we do”.
“We’ve carried out a thorough review of our ingredients and we have identified that the contaminated material was provided to us by an external third-party supplier,” a statement added.
Pret announced on Wednesday it will include full ingredient labelling on all of its products and the Government is considering a law change after the death of Natasha, from Fulham, south-west London.
She collapsed on board a flight in July 2016 after eating an artichoke, olive and tapenade baguette she had bought in Heathrow Airport.