Melbourne faces the prospect of its first major tram strike in almost two decades, after the union for Yarra Trams' staff lost patience with the slow pace of negotiations and applied to the fair work umpire for a vote on industrial action.

An unlimited number of 24-hour tram stoppages tops the list of disruptive measures the union has threatened to take against Yarra Trams, as talks on a new enterprise bargaining agreement turn hostile.

Melbourne could be brought to a halt by 24-hour tram strikes. Credit:Chris Hopkins

The union seeks an 18 per cent pay rise over three years, and has written to all members stating that Yarra Trams has offered a rise of just 1.33 per cent a year unless its staff agree to a string of productivity gains.

Phil Altieri, secretary of the tram and bus division of the Rail Tram and Bus Union, said Yarra Trams was already reaping the benefit of productivity gains from its staff, who had helped bring down fare evasion to record lows this year and improve on-time running to its best levels since the operator took over the system in 2009.