More than 600 people face losing their jobs after an appeal tribunal confirmed a ruling which could force ferry business MyFerryLink to close within six months.

The long-running legal saga took its latest twist today as Eurotunnel, the owners of the Dover to Calais operator, learned its case to keep the business afloat had been rejected.

The Folkestone-based company will now put the operator up for sale after the Competition Appeal Tribunal confirmed it has to stop operating ferries on the route because it risks putting rival operators, P&O Ferries and DFDS, out of business.

Eurotunnel branded the decision “illogical” saying it will reduce competition and is “contrary to the interests of free trade”.

The Competition and Markets Authority believes its ownership of the ferry company gives it too large a share of the cross-Channel market, given its ownership of the Channel Tunnel.

Eurotunnel’s chairman and chief executive Jacques Gounon said: “MyFerryLink is an operating and commercial success.

“We are proud to have succeeded where so many others have failed.

“Given the position of the British authorities, the future of MyFerryLink will now be determined outside the group”.

The rejection confirms a ruling originally made in June 2013 by the Competition and Markets Authority, then known as the Competition Commission, which said the operation broke monopoly rules.

Eurotunnel launched MyFerryLink in August 2012 after acquiring three vessels which previously belonged to SeaFrance, before the company went into administration.

The legal saga began following an original ruling in June 2013 by the Competitions and Markets Authority, then known as the Competition Commission, which said Eurotunnel’s ownership of MyFerryLink gave it too much share of the cross-Channel market.

This was quashed by the Competition Appeal Tribunal in December 2013 but the Competition and Markets Authority announced, once again, it had to close within six months when it ruled again on the decision in June last year.

The Folkestone company then argued its ownership of the ferries constituted an acquisition of assets, rather than a merger, thus not breaking monopoly rules.

The Competition Appeal Tribunal today rejected Eurotunnel’s appeal of that decision.

The ruling retriggers the six-month timetable for the operations to cease, putting 600 jobs at risk, of which about 100 are based in Dover, unless the business can be sold.

Eurotunnel must cease operating ferry services at the Port of Dover for two years and would not be able to use the Berlioz and the Rodin vessels it bought from SeaFrance for 10 years.

The Competition and Markets Authority's Eurotunnel Inquiry Group chair Alasdair Smith said: “Our first priority remains to protect the interests of passengers and freight customers.

“With two of the operators on the Dover-Calais route making substantial losses, it remains our view that the current level of competition on the route is unsustainable and likely to lead to the exit of a competitor..." - Competition and Markets Authority's Alasdair Smith

“With two of the operators on the Dover-Calais route making substantial losses, it remains our view that the current level of competition on the route is unsustainable and likely to lead to the exit of a competitor.

“Having one of only two ferry operators owned by the competing rail link would be bad for customers.

“It would be much better for passengers and freight customers to have three competing cross-Channel operators – with Eurotunnel running the rail link and two independent operators on the ferry route.

“The order would stop MyFerryLink running services out of Dover while it is owned by Eurotunnel but we would not prevent Eurotunnel from finding a suitable purchaser that was completely independent of Eurotunnel to operate the ferry service.

“We are conscious of the potential effect of our decision on the jobs of the MyFerryLink workers.

"However, there will also be job losses if MyFerryLink remains on the route and another operator leaves.”

The Port of Dover said it would try to minimise any negative impacts for passengers.

Chief executive Tim Waggott said: “Our immediate thoughts are with those who are directly affected by this decision.

“We will continue to consult regularly with all of our major ferry customers, and community groups, in the days and weeks ahead as we plan our way forward to future success.”