Holidaymakers returning to Wales from the Greek island of Zante are to be asked to quarantine for 14 days and be offered Covid-19 tests, the Welsh Government has said.
Health and social services minister Vaughan Gething said public officials had identified “multiple separate clusters” linked to the popular holiday island.
Currently there are no quarantine restrictions in place for people returning to the UK from Zante.
The first Tui flight affected will land tonight at Cardiff International Airport and passengers will be given a letter asking them to self-isolate for two weeks.
They will also be offered a coronavirus test within 48 hours of their arrival home and a repeat test eight days after returning.
Mr Gething said he was also asking for a meeting with the UK Government and the other devolved nations to discuss further measures.
“There are currently six clusters amounting to over 30 cases in the last week from four flights, of which two of these flights landed in England,” he said.
“There are concerns from our public health teams that the current advice and control measures for returning travellers are insufficient.
“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.”
Mr Gething added: “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.
“This is a dynamic situation and I will continue to review what measures may be required in the future.”
Tour operator Tui later said it would no longer be offering holidays to the resort of Laganas on Zante from Thursday.
Andrew Flintham, managing director of Tui UK and Ireland, said: “The recent cases in Wales have highlighted a demographic of customers that have recently returned from Zante and subsequently tested positive. As the only airline that flies between Cardiff and Zante it has allowed us to understand trends that may also be seen in other areas of the UK.”
The new measures follow reports that passengers on a flight from Zante to Cardiff last week did not adhere to coronavirus rules.
Public Health Wales has confirmed at least 16 cases of Covid-19 from three different parties who were on Tui flight 6215 to Cardiff on August 25.
Seven of those were infectious at the time of flying and all 193 passengers have been told to self-isolate, it said.
One traveller claimed that the flight was full of “selfish ‘covidiots’”, with passengers not wearing their masks properly and disregarding the rules.
On Tuesday, Public Health Wales said one further person with coronavirus had died in Wales, bringing the total number of deaths there to 1,596.
There were a further 51 positive cases of Covid-19 reported, bringing the number of cases to 18,063.
In a statement, Tui said that cabin crew and other passengers confirmed there were multiple warnings about wearing face masks on the flight.
“The health and safety of passengers is always our priority, our crew are trained to the highest standards,” a spokeswoman said.
“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.”