Regional train services could be affected after train workers applied to take protected industrial action as part of negotiations with V/Line.
The Rail, Tram and Bus Union has applied to the Fair Work Commission for the ability to hold work stoppages up to 48-hours long.
The union shut down Melbourne's CBD in September with the first train and tram strikes in a generation as part of negotiations with Metro Trains.
Public Transport Minister Jacinta Allan said talk of strike action was all speculation and negotiations were continuing.
The union last year won a 17 per cent pay increase over four years for Metro operational staff.