Low-cost airline Jet2, which operates routes from Stansted Airport in Essex, has delayed the restart of flights and holidays to July 1.
The provider had hoped to restart its services on June 24, but this has been pushed back after several changes to the travel lists were made by the government on Thursday.
Portugal has now been moved to the amber list from green - a decision which has come under fire from travel agents.
Transport Secretary Grant Shapps said the government is taking a "safety first attitude" towards travel.
Steve Heapy, chief executive of Jet2.com and Jet2holidays, said: "We agree that public health must be the number one priority. However, despite all the evidence and data showing that travel can restart safely and at scale, the UK continues to remain largely grounded whilst the rest of Europe opens up."
Stansted Airport bosses have also hit out at the government's decision, arguing destinations are being left off the green list "despite clear evidence they are safe to visit".
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