Greece has banned Brits from holidaying there until July 15.
The Greek government had previously said it would resume flights between the two countries on June 15.
But officials later reversed this decision and delayed the reopening until July 1.
But Greece has now extended its ban on flights from the UK until July 15.
Flights will remain restricted even after Greece reopens its borders to international visitors on Wednesday, sources told the Athens News Agency.
The policy was agreed at a meeting of government officials chaired by prime minister Kyriakos Mitsotakis.
He reportedly said: "The whole opening procedure is dynamic and the data will be continuously evaluated."
Flights from Sweden are also included in the extended ban.
Tui, the UK's biggest tour operator, was due to serve four Greek islands when it resumes its operations for UK customers on July 11.
The announcement comes as the government is expected to reveal a new travel traffic light system for travelling this week.
The new system will decide which nations are safe to travel to, with those classed as green or amber available to holidaymakers.
Austria, Barbados, Croatia, Germany, New Zealand, Thailand and Greece are some of the countries that have been given the 'green' light, according to the Sun.
While Spain, Australia, Belgium and Italy are on the amber list.
The government has said the full list of countries and exemptions will be announced next week with people being able to go on holiday to those destinations the following week.
Under the traffic light system quarantine restrictions will be lifted for people returning from those countries on the green and amber lists.
However, it is unclear whether British nationals could still be forced into self-isolation as they begin their holidays.
The Sun Online reports that the two colours will cover every European nation.
The UK Government is understood to still be in air bridge talks with France, Spain, Italy, Germany and Greece.
This would mean UK travellers could go abroad, without any need to quarantine at their destination or when they travel back home.
