Eurotunnel dubbed the ruling “ridiculous” and pledged to appeal, while Transport Minister Frédéric Cuvillier gave it the French government’s full support.
“This judgement means a death sentence for the company and its 533 jobs in France and 71 in Great Britain,” Cuvillier said.
The government will “use all its resources” to enable the ferries to keep running, he said.
France’s competition regulator gave the go-ahead for Eurotunnel to run the Rodin and the Berlioz between Calais and Dover after it bought the boats off SeaFrance when it went bankrupt in 2012.
Apart from the Channel tunnel itself, MyFerryLink’s competitors in carrying freight and passengers are Danish operator DFDS and Britain’s P&O Ferries, both of which are losing money.
DFDS claims to claims to be losing 1.08-1.34 million euros a month due to MyFerryLink’s competition.
The CMA has given MyFerryLink six months to wind up the operation or find a way to make it completely independence of Eurotunnel.
Eurotunnel hit back with the claim that the move would establish a de-facto “duopoly”.