The deaths of a British couple who were staying at a hotel in Egypt’s Red Sea resort of Hurghada were caused by E coli bacteria, according to test results released by Egypt’s chief prosecutor on Wednesday.

John Cooper, 69, had acute intestinal dysentery caused by E coli, and 63-year-old Susan Cooper had haemolytic uremic syndrome (HUS), probably because of E coli, said the Egyptian general prosecutor Nabil Sadek.

He said the couple’s bodies showed “no criminal violence”; other tests on air and water at the hotel found nothing unusual. Thomas Cook evacuated 300 guests from the hotel as a precaution.

Their daughter, Kelly Ormerod, who was with them the night before they died, has said they used perfume to mask a strange odour in the room.

The forensic report denied there had been any leakage of harmful gases into the room. However, it detailed how the “unknown smell” noticed by Ormerod was “due to a leak of insecticide used in the next room”.

The report added that the insecticide, lambda-cyhalothrin, a chemical commonly used to control pests in home gardening or in agriculture to prevent insects eating crops, was safe to use, and denied that it had anything to do with the deaths.

The report added that the postmortems showed John Cooper died from a cardiac arrest after blockages to an estimated 80% of the veins in his heart. He also tested positive for the E coli bacteria, which caused the vomiting and diarrhoea he experienced shortly before his death. The report adds that he had consumed alcohol and hash, a kind of marijuana. There is no indication in the report that either contributed to his death.

Susan Cooper is detailed in the report as suffering from Hemolytic uremic syndrome, a condition that affects blood vessels and blood, and can occur after people are infected with E coli. The report mentions that it was suggested that she contracted E coli “as she was staying with her husband and had eaten the same food”.

The report also states that at 11.30am on the day they died, the Coopers’ daughter called doctors in the hotel to examine her parents. John Cooper was experiencing diarrhoea and vomiting and the “doctors gave him medicine they thought was appropriate, this being Ringer’s solution (rehydration salts) and a dexamethasone injection, a corticosteroid”. His condition worsened and he died in his room.

Ormerod said she had “no faith” in the Egyptian authorities’ claims, saying she wanted more transparency and would wait for the results of tests done by the UK Home Office before coming to any conclusions about how her parents died.

“Thomas Cook put a report out that there were high levels of E coli at the hotel. Whether the Egyptians have honed in on that, I have no idea.”

She expressed doubt that anyone could die so shortly after exposure to the bacteria, accusing the Egyptian authorities of seeking a quick answer in order to protect the nation’s tourism industry.

“I don’t know what tests they have done. The report I have seen, from the media, not sent to me, was very, very brief ... Exactly what have they tested for?”

She said she had been told the UK authorities were due to carry out a postmortem examination soon.

Thomas Cook said it was clear “something went wrong in August at the Steigenberger Aqua Magic hotel in Hurghada and that standards fell below what we expect from our hotel partners”.

The travel company said high levels of E coli and bacteria that could cause toxic shock syndrome were found at the hotel. Guests reported that some people were so ill they defecated involuntarily in the swimming pools, and some complained of being served undercooked and raw chicken as well as drinks from dirty glasses.

The Steigenberger hotel said: “We are deeply saddened by the tragic deaths. All of our thoughts are with the family. In addition to our full support of the authorities, the tour operator and the franchise partner, we are highly engaged in running our own investigations.”

After the attorney general’s reports release on Wednesday, Egypt’s tourism minister, Rania al-Mashat, said: “The causes of death, E coli bacteria, were medically determined by a team of internationally accredited pathologists, which I hope for the family’s sake will put an end to previous speculative suggestions of what might have happened.

“We will review the attorney general’s autopsy reports in fine detail to determine our next course of action to look after the welfare of our visitors.”

Thomas Cook is preparing a compensation package for customers who reported an illness while staying at the hotel in August. It has also rolled out a programme of “specialist hygiene assessments” to all its hotels that experience a higher-than-average reported level of sickness.

A spokesman said it had yet to see the Egyptian prosecutors’ full report adding: “We will need time for our own experts to review it. We are deeply saddened by the tragic deaths of John and Susan Cooper. We will continue to offer every support to their daughter Kelly and the rest of their family.”

Additional reporting by Adham Youssef

• This article was amended on 13 September 2018. Haemolytic uremic syndrome can occur after an E coli infection, but that complication does not occur often, as an earlier version said.