All holidaymakers on board a TUI plane returning to the UK from Greece have been told to self-isolate after an outbreak of Covid-19 cases were linked to the flight.
Passengers who travelled to Cardiff from the island of Zante on flight 6215, arriving August 25, have been told they must now remain at home and self-isolate.
The strict instructions from Public Health Wales come after the body announced on Sunday that three separate infectious parties were on board the flight.
At least seven confirmed cases of Covid-19 have since been linked to the plane.
Any traveller who has since shown symptoms has been advised to seek a coronavirus test as soon as possible.
Dr Giri Shankar, of Public Health Wales, said: "Cardiff and Vale Test Trace Protect and Public Health Wales have identified at least seven confirmed cases of Covid-19 from three different parties who were infectious on Tui Flight 6215 from Zante to Cardiff on 25 August.
"As a result, we are advising that all passengers on this flight are considered close contacts and must self-isolate.
"These passengers will be contacted shortly, but meanwhile, they must self-isolate at home as they may become infectious, even without developing symptoms. Anyone with symptoms should book a test without delay."
He added: "Our investigations into a number of cases of coronavirus have indicated that a lack of social distancing, in particular by a minority of the 20-30 year age group, has resulted in the spread of the virus to other groups of people.
"I would make a direct appeal to young people to remember that even if they feel that they would not be badly affected by Covid-19 if they were to test positive for it, if they were to pass it on to older or more vulnerable family members, friends or colleagues it could be extremely serious, even fatal."
