The boss of Thomas Cook has said it will take more than a week to establish how a couple died while on holiday in Egypt.

Chief executive Peter Fankhauser pledged to “get to the bottom” of the deaths of Thomas Cook travel agent Susan Cooper and her husband John at the Steigenberger Aqua Magic hotel in Hurghada last Tuesday.

Experts were testing food, water and air conditioning and the results would be available within ten days, he told Sky News on Sunday.

Thomas Cook evacuated 301 holidaymakers from the Red Sea hotel as a “precautionary measure” after the couple died. Many of the guests reported that they had been ill with food poisoning.

Meanwhile, Egyptian investigators said there was no evidence of toxic gas in the hotel room where the couple died.

Egyptian prosecutor Nabil Sadeq said a technical inspection of the hotel room could find no trace of toxic or harmful gas emissions or leaks.

The result of forensic analysis of samples taken from the bodies is expected.

The Red Sea governorate said medical checks by a health inspector revealed “no criminal suspicions”.

The couple’s daughter, Kelly Ormerod, who was also at the hotel, said she believed the deaths were not from natural causes.

She told the BBC that her daughter had smelt something “a bit funny” in Mr and Mrs Cooper’s room the night before they died and that they had “sprayed a little bit of perfume to try to eliminate the smell”.

She also described finding her parents gravely ill at about 11am the following day.

Thomas Cook described the circumstances around the deaths as “unclear” and it has launched an investigation.

Mr Cooper, 69, died in his hotel room at the resort at 11am on Tuesday after suffering a “sharp drop in blood circulation”, according to a statement by the Egyptian authorities.

His cause of death was listed as “sudden failure in the heart muscle and respiratory failure”.

Mrs Cooper, 63, who worked at Thomas Cook’s Burnley branch, was taken to hospital five hours later in a “state of fainting” and, although heart recovery work took place for 30 minutes, she died at around 5pm.

The hotel’s manager has said that there were “no indications” to support allegations of increased illness at the hotel. Thomas Cook said that the hotel scored 96% in its latest audit.