An Italian family has expressed outrage at a restaurant for chasing up a lunch bill payment, even though their teenage son died of an alleged violent allergic reaction after waiters gave him the wrong type of ice-cream.

Davide Perta, 16, who suffered from a severe gluten intolerance, died from suspected anaphylactic shock minutes after eating the ice-cream at a fish restaurant in San Giovanni Rotondo, Puglia, his family said. The ice-cream was mixed with biscuits containing gluten.

His parents claim they had sent a list of foods their son could safely eat to the restaurant in advance, including a type of ice-cream containing no biscuit.

Magistrates have now placed La Spiga restaurant owner, Andrea Marchesani, under investigation for suspected manslaughter as they await the outcome of toxicology tests and an analysis of the ice-cream.

But the restaurant saw fit to call Perta's family to chase payment of the €2,000 (£1,600) bill for the lunch on 8 August, at which 30 people celebrated the catholic confirmation of a family member.

"I did not want to believe it. It seems an absurd, barbarous and cynical request," said Davide's father, Luigi Perta. "It was like being stabbed in the heart. I don't have a problem with asking for the bill to be settled, but I do have a problem with the timing and the way they did it. Not a word of condolence or apology. Just a cynical request for cash."

As a lifelong suffer of Coeliac disease, Davide was allergic to gluten, the proteins found in wheat, rye and barley. The anaphylactic shock he allegedly suffered after eating the ice-cream biscuits can cause the face to swell and flush, as well as respiratory problems and death. Despite receiving mouth-to-mouth resuscitation from a family member who was trained as a nurse, Perta died on his way to hospital.

"The request for the bill was possibly made at an inappropriate moment," said Marchesani's lawyer Leonardo Maruzzi. "However, the call was made to the boy's uncle, who was due to pay the bill, not to his parents."

When the call was answered, Davide's mother was present. Grabbing the phone, she shouted: "Shame on you."

Mazurri said: "About 30 people ate and someone will have to pay the bill."