High levels of e-coli and staphylococcus bacteria have been found at an Egypt hotel following the deaths of two British guests., it has been revealed.
Thomas Cook said food and hygiene standards tests had been carried out with stark results.
On August 21 John Cooper, 69 and his wife Susan, 63, died after staying at the Steigenberger Aqua Magic Hotel in Hurghada.
John died at the hotel and Susan passed away at a nearby hospital on the same day.
It has since been revealed that Thomas Cook was successfully sued in July by a Welsh family after they suffered gastric illness while staying at the same hotel.
The family of four, from south Wales received £26,000 in compensation and costs.
The claimants became ill while staying at the Steigenberger Aqua Magic Hotel on a Thomas Cook package holiday in April 2016.
Following the tragic deaths of John and Suan Cooper, Thomas Cook commissioned an independent hygiene specialist and air quality specialist to conduct a series of tests at the hotel.
They said the tests on the food and hygiene standards identified a high level of e-coli and staphylococcus bacteria.
Thomas Cook said it is likely that the presence of e-coli and staphylococcus would explain the raised level of illness reported among guests at the hotel during this time, supporting their decision to remove 300 customers.
However, neither their independent specialists nor independent expert Doctor Vanya Gant believe these results shed any light on the still unexplained cause of death of Mr and Mrs Cooper.
The results of the autopsies being conducted by the Egyptian authorities are being awaited.
Thomas Cook said the results showed something went wrong in August at the Steigenberger Aqua Magic Hotel in Hurghada and that standards fell below what they expect from hotel partners.
The Steigenberger Aqua Magic Hotel remains on stop sale to Thomas Cook customers until further notice.
Tests were carried out across the hotel after specialists were granted access by Steigenberger Aqua Magic.
However, the specialists were unable to access the Coopers' hotel room, which has remained under the control of the Egyptian authorities due to their ongoing investigation.
The examination of air and water quality came back clear, Thomas Cook said.
There was no evidence of carbon monoxide and there were normal carbon dioxide levels in the vicinity of the room, they added.
Results also showed normal levels of chlorine in the swimming pools.
The tests did not identify the presence of shigella, listeria or salmonella.
Thomas Cook Chief Executive, Peter Fankhauser, said: "Everyone at Thomas Cook is deeply saddened by the tragic deaths of John and Susan Cooper while staying at the Steigenberger Aqua Magic Hotel in Hurghada.
"Susan was a longstanding and much-loved colleague of ours.
"We continue to await the results of the investigation being conducted by the Egyptian authorities and are working closely with the Foreign and Commonwealth Office to ensure we prioritise the very best interests of the Cooper family.
"However, the tests that Thomas Cook commissioned and announced today show that hygiene at the Steigenberger Aqua Magic Hotel during the month of August did not meet the standards we expect.
"I am very sorry for all our customers who fell ill while on a Thomas Cook holiday at this hotel."
Mr Fankhauser added: "These results, while not establishing the cause of the tragic deaths of John and Susan Cooper, have prompted us to commit further resource to tackle hygiene standards in those hotels where we identify a higher than average level of sickness.
"At any one time, Thomas Cook has more than 500,000 people holidaying with us somewhere in the world.
"We will continue to do all that we can to keep them safe and well on what should be the happiest weeks of their year."
The tests covered food, water and air and included tests on the swimming pool, carbon monoxide and carbon dioxide levels, air conditioning units, and a thorough audit of food storage, preparation, presentation and equipment.
Preliminary results have been reviewed by Doctor Vanya Gant, the Consultant and Divisional Clinical Director in Microbiology and Infection, University College London Hospitals NHS Foundation Trust.
The findings have also been shared with the Cooper family, the Egyptian authorities and the Deutsche Hospitality group which has a franchise agreement with the Steigenberger Aqua Magic Hotel.
Thomas Cook have now taken the decision to roll out a programme of specialist hygiene assessments to all hotels which experience a higher than average reported level of sickness.
They are putting together a compensation package for all customers who stayed at the Steigenberger Aqua Magic Hotel in Hurghada during August who reported they were ill.
A dedicated team has been formed to prioritise complaints from the hotel.
