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.
Speaking last week on Radio 4’s Today programme, tourism minister Haris Theoharis said: “The final decision, from the UK and our point of view, will be in place in the next few days and I’m hoping the announcement will be positive from both sides.”
And he confirmed there was no need for those returning to the UK from Greece to be quarantined.
He continued: “The point is that Greece is a safe country – we have proven that during this crisis and we will continue proving this in the exit stages of the health situation.
“We feel that the risk of someone contracting the disease in Greece is much lower than most of the countries in Europe and indeed the rest of the world.
Put to him that there was no point in the quarantine from those returning from Greece, Mr Theoharis replied: “Correct.”