A potential change to the flagging of Color Line ferries has met with a backlash from unions and politicians.

Norwegian media are reporting that the government has proposed changing regulations to allow the owner to switch its two Oslo to Kiel ro-paxes from the NOR register to the Norwegian International Ship Register (NIS).

This would allow the company to replace 700 Norwegian crew with cheaper overseas personnel.

Color Line has been contacted for comment, while the Norwegian trade and industry ministry has been contacted over the likely timetable for any such move in the nation's budget announcement this week.

Maritime Danmark cited Danish MP and former minister of transport Magnus Heuniche as saying that he fears a domino effect if the rule is changed.

“More and more actors in the North now fear a domino effect as a result of a Norwegian decision that will destroy what until now has been a good job market with Nordic salaries and working conditions”, said Heuniche.

Fjord Line, DFDS, and unions across the Nordic region reportedly oppose the decision.