Video report by Owain Philips
The Welsh Government has announced that all passengers returning to Wales from Zante must self-isolate for the next 14 days to limit the spread of coronavirus.
It also said all those returning from the Greek Island will be offered a coronavirus test within 48 hours of their return and will be offered a repeat test eight days after returning home.
It comes after Public Health Wales confirmed at least 16 cases of Covid-19 from three different parties were on a Tui flight to Cardiff on 25 August.
Health Minister Vaughan Gething said public officials had identified "multiple separate clusters" linked to the popular holiday island.
Passengers arriving at Cardiff from Zante on Tuesday night were not told about the decision to impose self-isolation until they arrived back to Wales.
One passenger said he found out when he saw news articles on his phone.
''When we landed, I put my phone 4G on and on the internet the news came up that the flight has to self-isolate,'' passenger Joe Vincent said.
''Everyone was really angry. There was one family with a self-employed electrician and he couldn't work. He was really angry, his kids couldn't go back to school.''
Health Minister Vaughan Gething MS said: "Public Health Wales have expressed direct concerns about the public health risk posed by passengers returning to Cardiff this evening from Zante/Zakynthos. I share that concern. It is almost certain that travellers returning to Wales from areas of higher Covid-19 incidence will lead to further seeding of infections within Wales. Travel into Wales from mainland Europe drove the first wave of Covid-19.
"Without action it is likely that there will be significant health and economic impacts arising from new clusters of infections and renewed disease transmission in Wales. I have therefore agreed the following actions:
"I am aware that travellers may be returning to Wales from Zante/Zakynthos this evening or tomorrow from other airports outside of Wales. I ask that these travellers self-isolate for 14 days on their return and request a test once they arrive home and to repeat the test eight days after returning home.
"In addition, I have pressed for an early meeting with the UK government and devolved nations tomorrow to consider the latest assessment of risk by the Joint Biosecurity Centre. There is an obvious need for us to consider the potential for changes to the Regulations in Wales which would require travellers arriving in the UK from Greece and possibly elsewhere to self-isolate on their return."
The UK Government now faces growing pressure to reconsider quarantine rules for Greece after the measures introduced by the Welsh Government.
On Tuesday, tour operator TUI announced it would no longer be offering holidays to the resort of Laganas on Zante.