Around 170 passengers aboard a flight from the Greek island of Zante touched down at Cardiff airport at 10.46pm on Tuesday to discover that the rules had changed while they were in the air – and they would be required to self-isolate for two weeks.

At the same time, many Scottish travellers in Greece began studying flight schedules in a bid to return home before 4am on Thursday, when a general quarantine obligation begins.

The Welsh move was announced by the health minister, Vaughan Gething, after six clusters amounting to more than 30 cases of coronavirus had been traced to just four flights.

“There are concerns from our public health teams that the current advice and control measures for returning travellers are insufficient,” he said.

“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 are concerns in Wales about infections that may be brought back via airports outside the country; two of the four flights landed in England.

“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,” said the minister.

On arrival, passengers on the plane from Zante to Cardiff, Tui flight 6215, were handed letters instructing them to quarantine.

They were informed they will be given two Covid-19 tests: one within 48 hours and another after eight days from their return.

Ironically, that is the testing regime that many senior figures in the travel industry are demanding as an alternative to 14 days of quarantine.

Sixteen infections have been linked to the corresponding Zante-Cardiff flight a week earlier, on which some passengers have complained of poor behaviour.

Tui, Britain’s biggest holiday company, has announced it has cancelled all future holidays to the resort of Laganas on Zante for 2020.

Andrew Flintham, managing director of Tui UK, said: “Laganas is a popular resort with young people who traditionally holiday in large groups of friends. The health and safety of our colleagues and customers is our primary concern and recent cases shows that some customers are not following social distancing and Covid safety measures.

“It is therefore the right thing to do to protect and reduce a now-identified potential risk to others by no longer offering holidays to this specific resort.

“The recent cases in Wales have highlighted a demographic of customers that have recently returned from Zante and subsequently tested positive.

“We believe that with good track and trace processes, testing at airports and a nuanced approach to regional travel corridors, customers can continue to travel safety.”

Earlier, Scottish travellers were given 30 hours to race back from Greece to avoid two weeks in self-isolation.

The justice secretary, Humza Yousaf, tweeted: “Travellers from Greece will be required to self-isolate for 14 days on arrival in Scotland from 4am Thurs morning (3 Sept).

“This is due to significant rise in cases of Covid-19 imported into Scotland by people who have been to Greece. Decision made in interest of public health.”

Scottish holidaymakers who cannot afford the time to self-isolate face limited options and high fares for short-notice flights home.

The normal connecting hubs of Amsterdam and Paris are not available, since the Netherlands and France have lost their quarantine exemption. A one-way flight on British Airways from Athens via London Heathrow to Glasgow on Wednesday evening is selling for over £400.

Mr Yousaf said: “With Scotland’s relatively low infection rate, importation of new cases from Greece is a significant risk to public health.

“People should think very hard before committing to non-essential travel abroad.”

Mike Tibbert, vice president of the Scottish Passenger Agents’ Association, called the situation a “hokey cokey of countries which are ‘in or out’,” which made it impossible travel firms to run a business.

Tui has said it will offer holidaymakers from Scotland with imminent trips booked the opportunity to cancel for a full refund or change dates or destinations.

Tuesday evening's moves represent the biggest fracture so far between the four nations of the UK over quarantine policy.

They had mostly been aligned, although Scotland was slower to give the all-clear to Spain – now on the “no-go” list once more – and imposed self-isolation on arrivals from Switzerland a week ahead of the other nations.

But now Wales has introduced a new dimension, targeting a specific island – a strategy that the UK government has been consistently against.

The Scottish and Welsh decisions came at the end of a day on which the chief executive of British Airways’ parent company, IAG, described the approach to quarantine as “chaotic”.

Willie Walsh said: “Enforced quarantine from an ever-shifting list of countries isn’t effective.

“Healthy people shouldn’t be locked up for 14 days simply because they have been travelling.”

The Department for Transport said no changes to its rules for England had so far been made.

But with Portugal looking increasingly likely to lose its quarantine exemption just two weeks after it was granted, holidaymakers are scrambling to return from Lisbon, the Algarve and the islands of Madeira and the Azores before 4am on Saturday – which is when the measure is believed most likely to take effect.