With Greece on the brink of leaving the euro, government officials have warned UK tourists to "take enough money to cover emergencies" if they are heading there this week, as there is a danger that cash machines in the country could be turned off.
Concerns have also been raised for for Greek citizens following predictions that the country’s economic meltdown could lead to a food shortage and problems with medical supplies.
This could go on to spark violence and riots in the streets of Athens and across the country.
George Osborne said: “Britain must be prepared for the worst.”
Tour operators say that customers in Greece and those flying out this week should take "plenty of cash and a mixture of other payment methods so that they are covered in all situations."
Travellers are being given additional safety deposit boxes when they arrive in Greece.
Staff in some resorts will hand out euros if the banks shut and put a charge on their customers' debit or credit cards.
They are now working alongside Whitehall officials to prepare for a mass evacuation of 110,000 tourists if Greece does crash out of the euro.
If this happens, it would be the largest peacetime evacuation of Britons.
Yesterday the Foreign Office admitted officials had been in talks with the Association of British Travel Agents to formulate evacuation plans.
A spokesman said: "There have been conversations across Whitehall planning for all contingencies, and part of that is how we can give advice for travelling Britons.
"We are waiting at the moment to see how matters unfold, but the trigger could be on Monday or even over the weekend."
The country’s economic woes have already affected island airports.
According to new reports, night flights in and out of Lesbos were stopped after its airport ran out of money to maintain electronic landing systems.
And at least three other popular tourist destinations – Kos, Skiathos and Santorini – are said to face similar problems.
However officials have said that it is "very unlikely" that British tourists will be left "stranded" in the country.
Greece owes an estimated £172 billion to a series of international organisations, including the European Commission, European Central Bank and International Monetary Fund.
The country has less than a month to find £4.8 billion euros to begin repayments - and needs to strike a deal with the ‘Troika’ of lenders keeping it afloat.
In a bid to win more time for a deal to be made, the European Central Bank piled an extra £3 billion into Greek banks.
However this will only tide the counter over until Monday’s emergency talks, as savers are worriedly withdrawing up to £1 billion a day.
Finance minister Yanis Varoufakis said the EU faced a “stark choice” on whether to strike a deal to save Greece from bankruptcy.