On Sunday Greek police will start implementing a new passport control system, as the country finally comes in line with a 2017 EU law.
The new system results in additional checks on travellers going to and from areas outside the Schengen zone, which could result in increased waiting times.
The Foreign Office has warned Brits to arrive at the airport “in good time”, the Daily Mail reports.
In March 2017 the EU passed a directive to reinforce checks at external borders.
The Schengen Borders Control regulation obliges all member states to carry out systematic checks on all persons, including those enjoying the right to free movement under EU law, when they cross all external borders.
Although other countries began implementing this two years ago, Greece was given an extension because they were not ready for it.
Greece will begin upholding the regulation from April 7.
The travel advice on the Foreign Office website says: “As of 7 April 2019, the Hellenic Police will begin implementing systematic passport control checks for all European citizens travelling to/from destinations outside the Schengen area (including the UK) in line with a 2017 Schengen Borders Code regulation.
“Increased waiting times at passport control are possible on departure from and arrival into Greece. You should ensure you arrive at the airport in good time.”
Greece is a popular tourist destination, and attracts more than 3million Brits each year.
The Schengen Area comprises 26 European states, including: France, Germany, Netherlands and Spain.
The group of countries, named after the agreement which was signed in Schengen, Luxembourg in 1985 abolished all passport and other border checks at their mutual borders.
The UK and Ireland opted out of joining the zone in 1997 when it became part of the EU charter.
Bulgaria, Cyprus, Croatia and Romania are all set to joint the Schengen zone.
Not all members of the EU are part of the Schengen zone, such as Switzerland, Iceland and Norway.