The EU court has ruled that Finnish ferry operator Viking Line had the right, known as "freedom of establishment", to ignore collective agreements made with Finnish unions, re-flag its vessels to Estonia and recruit local crews on lower pay.

RMT general secretary Bob Crow warned that the ruling will be used by employers impose lower wages across the EU on the basis that any action, such as against flags of convenience, ‘restricts the right of freedom of establishment’.

“This unaccountable EU court has ruled that the right to strike, supposedly enshrined in EU law, is now ‘subject to certain restrictions’ and is only subject to ‘national law and practices’.

“As a result, not only will Tory anti-union laws remain in place here, but the right to strike in Finland is also illegal if it is deemed ‘contrary to good morals’ or is prohibited under EU law.

“This underlines the need for a referendum on the renamed EU constitution as it hands huge powers to EU institutions like the ECJ which lack any morals themselves and serve the interests of big business in the name of ‘free movement’,” Bob Crow said.