In a statement, Egyptian prosecutor Nabil Sadeq said a technical inspection of the hotel room could find no trace of toxic or harmful gas emissions or leaks. It also says his office is waiting for a forensic analysis of samples taken from the bodies.
The Steingenberger Aqua Magic Hotel had an overall score of 96% on Thomas Cook.
Mr Cooper died in his hotel room at the Steigenberger Aqua Magic resort at 11:00 local time on Tuesday, according to a statement by the Egyptian authorities.
Receive IOL's top stories via WhatsApp by sending your name to 0745573535.
She said they were "fit and healthy" before their holiday and in "perfect health" just hours before being taken ill.
The air conditioning system at a hotel where a British couple died in unknown circumstances while on holiday in Egypt is sound, the public prosecutor said on Saturday, citing a report by engineering experts.
The evacuation was made by famed travel agency Thomas Cook as a "precautionary measure" although it in unclear to what.
The couple's daughter, Kelly Ormerod, said: "I believe their deaths are not due to natural causes".
She explained that they had all enjoyed a meal together before the Coopers went to bed at around 1.30am.
He said: "We are deeply saddened by the deaths of two of our customers while on holiday in Hurghada in Egypt, one of whom was a loyal and long-serving member of our Thomas Cook family". Susan Cooper was taken to hospital after fainting and died there, it said.
Ormerod said the family were in "utter shock" as they awaited results of post-mortem examinations on her parents.
"We will be contacting those customers due to travel to the Steigenberger Hotel in Hurghada in the next four weeks to offer alternative holiday options".
Thomas Cook swiftly offered its customers at the hotel the chance to either move to another resort in Hurghada or fly home.
He said: "The food, the temperatures of the food, things like that".
But the hotel management told AFP there were "no indications to support allegations of an increased incidence of illness".
"The manager of Thomas Cook is the most rude man I ever met".
The Governor of Hurghada's office said the cause of John Cooper's death was "a sudden stoppage of the heart muscles and respiratory failure", while Susan died of "a stoppage of circulation and respiratory failure".
"Half the time we don't know what it is and can't eat it because it's raw in the middle".
Thomas Cook had earlier released a statement reacting to the incident and explaining why they took the step of removing their guests from the hotel.