Greece imposed a national lockdown from Saturday in a bid to limit a second wave of Covid-19.
The nationwide measures for three weeks include a ban on travel between different parts of the country except for “essential reasons”.
The Foreign Office warned that Greek domestic flights, inter-city buses, trains and ferries are “liable to disruption”.
While hotels, private rental accommodation and hostels are permitted to open, many are likely to close due to the new restrictions.
The lockdown in Greece will be in place until at least November 30 but have the potential to be extended, according to the FCDO.
Greece is one of a declining number of countries on the UK’s travel corridors list but Covid lockdown measures in England until December 2 limits foreign travel to just work, education or other “legally permitted reasons”.
Anyone going to Greece from Monday will need to complete a passenger locator form at least 24 hours before travel or face a €500 fine on arrival. Proof of a negative Covid-19 test taken within 48 hours of arrival by air will also be required.
Those travelling by road, rail or ferry will have to prove a negative test taken within 72 hours before arrival.
The Greek lockdown forced Costa Cruises to suspend sailings to the country by Costa Deliziosa.
Prime minister Kyriakos Mitsotakis said the Greek government hoped some degree of normalcy will return as the Christmas holidays approach, but restrictions will still be in place.