Workers on the Tyne and Wear Metro are to be balloted for strikes in protest at the Government's 1% pay cap.
The Rail, Maritime and Transport union said its members employed by NEMOL are classed as local government employees and are caught in the "trap" of a pay cap.
RMT general secretary Mick Cash said: "We have listened intently and considered the views of our NEMOL membership, who through democratic channels have made their position abundantly clear that they are prepared to fight for pay justice irrespective of being caught up in the Government's 1% pay cap.
"With inflation running at 4% our members should not be forced through centrally imposed austerity measures to take a hit on their standards of living just to bail out a Government which seems to have plenty of cash available when it comes to looking after mates in the private train companies and beyond.
"Preparations for the ballot are under way."