Forming the second part of a £150m investment approved in 2013, the expansion follows a near 90 per cent increase in long haul traffic at the terminal last year thanks to new routes to the Middle East and America.

The first step saw a £25m terminal extension with a retail wing (pictured below) which was unveiled in October.

Scotland’s busiest terminal, which handles 10 million passengers a year, will see a new 2000 square metre rapid-build immigration hall and a bigger structure will be built around it over the next five years.

The work also includes new stands for aircraft to park, and “air bridges” to link them to the terminal.

Construction starts next week and will take four years, with 50 jobs being created.

Prime minister David Cameron visited the site yesterday to see the plans.

He said: “The expansion of Edinburgh Airport is great news for Scotland and for the whole of the UK. It will open the door to more long-haul flights and new routes, meaning more tourism, more trade and more jobs for people here in Edinburgh and beyond.

“It will also help Scotland to compete on an international scale and of course the UK’s large network of embassies across the globe will continue to keep banging the drum for Scotland and help maximise any opportunities, whether it is bringing in overseas investment or supporting businesses in Scotland to export worldwide.”

He was shown around by airport CEO Gordon Dewar who explained what the changes would mean.

Mr Dewar added: “We’ll effectively be creating a new international facility for our airlines, and underpinning our future aspirations to increase passenger numbers and enhance their experience and be one of the leading European airports for our size.

“We’ve grown significantly over the last several years and have worked hard to redefine our airport strategy with the passenger at the core of everything we do. It’s wonderful that we can showcase the ongoing investment in Edinburgh Airport and our plans for continued growth to the Prime Minister and to the millions of passengers which travel through here each year.”