It is thought the expansion, which will include a new retail wing, will help cut waiting times at check-ins and provide a boost to the shopping experience at arrivals.

The extension is the first step in a £150m investment plan that will transform sections of Scotland’s busiest airport over the next five years.

A second entrance to the airport has been created in the arrivals lounge that will now boast four new shops and a number of airport offices, including extra ticket desks to speed up the check-in process.

Passengers will be able to enter and exit the new extension – sited close to the airport’s tram stop – from the domestic arrivals area.

A state-of-the-art security hall on the second floor of the expansion will also have a dedicated fast-track link bridge from the airport’s multi-storey car park.

Under the plans, the existing security hall will be transformed into duty free shopping as part of the second phase of development taking place next year.

An outdoor “community plaza” area is also set to open at Easter 2015, connecting the new extension with the tram stop, coach park and car rental centre.

Construction of the £25m revamp began in October last year.

Gordon Dewar, chief executive at Edinburgh Airport, hailed the completion of the first phase of the project.

He told Edinburgh Evening News: “We’ve reached another milestone and having the ground floor of our new terminal extension now open is great news for our passengers.

“A huge amount of work has gone into the design and ­construction of the project and it’s hard to believe that less than a year ago the site was our coach park.

“This summer we experienced more passengers than ever before so it’s important that we continue to invest in our facilities.

“With a new Marks & Spencer store recently opened and final preparations being made for more new shops and ­services, we’re looking forward to giving our passengers a great airport experience.”