The TUC opposed the EU services directive that will enable migrant workers to be paid in their country of origin. This would allow companies to pay workers from Eastern Europe average wages in their own countries, far less than the British minimum wage. Unions fear this will trigger a "race to the bottom" for pay and conditions.
The vote marks a shift towards Euroscepticism by the unions, which have broadly supported the EU in recent years, believing closer ties would deliver better working conditions.
Although some unions have had reservations about Europe in the past, they have been counterbalanced by pro-European unions, such as Amicus. But even Amicus has changed its tune and backed the Eurosceptic motion to oppose any revival of the EU constitution.