The Egyptian authorities have confirmed that there was a "strange smell" in the hotel room where Burnley couple John and Susan Cooper died.
Major General Ahmed Abdullah, governor of Egypt's Red Sea region where the Steigenberger Aqua Magic Hotel in Hurghada is located, confirmed on the region's Facebook page that "there was a strange odour in the room."
This supports the claim made by the couple's daughter, Kelly Ormerod, that there was a strange smell in the room which they tried to eliminate with perfume.
Kelly, who was holidaying with her parents and her three children, has stated she believed it was "something in the room" that killed her mum and dad.
She said they noticed the smell after returning to their rooms after dinner. Her daughter requested to sleep with her grandparents but Mr Cooper returned her to the room where Kelly was sleeping at around 1-30am as she was complaining about the smell.
When her parents failed to come down for breakfast the next day Kelly went to their room where she found them both seriously ill.
Mr Cooper, died in the room while Mrs Cooper, who has worked at the Burnley branch of Thomas Cook for many years, died after being taken to hospital, according to their daughter.
The room was sealed off while specialist engineers inspected ventilation and air conditioning systems.
The Coopers' bodies are being analysed by a forensic laboratory in capital Cairo, the governor added.
Mr Abdullah also responded to claims a large number of the hotel's guests had suffered from "severe fatigue".
He said only 23 of the hotel's 1,995 guests visited the on-site clinic or requested medical assistance in the last week, just 1.2% of the total number of visitors.
The governor said those guests feeling unwell had been found to be suffering from stomach cramps, for example, as a result of swallowing seawater; while others had spent too long in the sun.
Travel operator Thomas Cook ordered the evacuation of all of its guests staying at the hotel in the wake of the Coopers' deaths last Tuesday.
Mr Abdullah claimed 160 of 261 guests refused to leave the Hurghada resort, which he said "shows the confidence of the British tourist" in the safety of the region's hotels.
But a Thomas Cook spokeswoman disputed those figures and said that only a "very small number" of around 300 guests refused an offer to move hotels or return home to the UK.
Those who remained were required to sign a disclaimer stating it was their own decision to stay at the hotel, the spokesman added.
At the weekend, officials said an inspection of the Coopers' hotel room revealed there were no toxic or harmful gas emissions or leaks.
Thomas Cook chief executive Peter Frankhauser has said there is "no evidence" of carbon monoxide poisoning.
The firm's own specialists, who have analysed food, hygiene systems, water and air conditioning at the hotel, are expected to report back with findings next week.