Tui said it is “confident” that its crew followed guidelines about masks onboard a flight from Zante to Cardiff last month.
The operator investigated the August 25 flight, after 16 passengers from different groups tested positive for Covid-19.
Passenger Stephanie Whitfield told the BBC that many of those on the flight were talking and not wearing masks.
Tui said today: “Passengers are informed prior to travel and via PA announcements on the flight that they have to wear masks throughout and are not allowed to move around the cabin.
“Masks can only be removed when consuming food and drink.
“Following an initial investigation with our cabin crew, we are confident that multiple announcements via the PA and individual conversations with customers to try to reinforce protocols took place and other customers on the flight have confirmed these findings to be correct.
“We remain concerned that Mrs Whitfield didn’t speak with the crew during the flight or before August 31.”
All the passengers on the flight have been told to self-isolate for a fortnight.
The incident prompted headlines in the national media about ‘covidiots’ who were not wearing masks properly on the plane.