In a plot twist worthy of a Nordic Noir serial, the Lord Mayor of Copenhagen has dented Ryanair’s plans to make a killing with its new base in the Danish capital.

Frank Jensen, a Social Democrat who has been the city’s Lord Mayor for five years, has banned staff from flying with Ryanair while on official business - even if it means paying much more on the Scandinavian airline SAS.

Copenhagen has 45,000 municipal workers.

Mr Jensen told the Berlinske newspaper: “We require all of those who deliver services to the municipality, including those who would sell us plane tickets, to offer their employees proper salaries and working conditions.”

On his Facebook page, he described Ryanair’s practices as “social dumping.”

Ryanair responded by tweeting a picture of Mr Jensen’s face superimposed on Marie-Antoinette’s body, with the slogan: “Let them eat cake!” and “Let them pay high fares!”

Best low-cost airline in Europe awards Show all 10 1 /10 Best low-cost airline in Europe awards Best low-cost airline in Europe awards 1. Norway Airlines Norwegian flies to over 126 destinations, and recently introduced long-haul flights to New York and LA Best low-cost airline in Europe awards 2. EasyJet Airlines British airline easyJet operates domestic and international scheduled services on over 600 routes in 32 countries. Getty Best low-cost airline in Europe awards 3. Germanwings Airlines Cologne-based Germanwings flies to destinations and airports across Europe Getty Best low-cost airline in Europe awards 4. NIKI Airlines Unlike many airlines described as low-cost, NIKI does provide free refreshments, newspapers and baggage on some services Best low-cost airline in Europe awards 5. AirBaltic Airlines Latvian low-cost carrier AirBaltic flies to over 50 destinations including Rome, St. Petersburg, and Prague Best low-cost airline in Europe awards 6. Wizz Air Airlines Hungarian low-cost airline Wizz Air serves 35 countries Best low-cost airline in Europe awards 7. WOW Air Airlines Iceland's low-cost airline operates flights to 16 destinations including London, Milan and Barcelona Best low-cost airline in Europe awards 8. Pegasus Airlines Turkish based Pegasus Airlines flies to 97 destinations Best low-cost airline in Europe awards 9. Onur Air Turkish based Onur Air operates flights to 80 destinations in 20 countries Best low-cost airline in Europe awards 10. FlyBe Airlines Devon-based Flybe operates over 180 routes to 65 European airports

The Dublin-based airline has a long history of striving to avoid what it sees as onerous labour laws by employing crew on contracts written under Irish law. The Danish trade-union movement is seeking to have this practice overturned, with a case set for next month.

Ryanair, which is the biggest budget carrier in Europe, set up a base in Copenhagen this year. It had previously offered flights to the city, though rather than landing in the Danish capital they actually touched down at Malmo in Sweden - on the other side of the bridge between the two nations.

Copenhagen is already experiencing strong low-cost competition, with Norwegian and easyJet taking on SAS. Ryanair’s schedule from the capital serves a dozen cities, including London Luton, Madrid and Milan Bergamo.

A spokeswoman for Ryanair told The Independent: “Ryanair's pilots and cabin crew enjoy high pay, job security and already have a collective agreement with Ryanair. We are also surprised at his boycott call when all Ryanair flights in Copenhagen being handled by workers who are represented by Danish unions.

“SAS is cutting flights, closing routes, cutting pensions, cutting pay and cutting jobs. Which model does Mayor Jensen prefer to support? SAS's jobs cuts, pension cuts and pay cuts or Ryanair's growth?”