The referees are threatening to take industrial action on the eve of the finals as their pay war with the NRL escalates.

The Professional Rugby League Match Officials (PRLMO) on Wednesday notified the NRL that it will ballot its members to seek their approval for industrial action. It is the first time in the history of the game that whistle-blowers have taken the landmark step, the result of frustrations in negotiating a new enterprise bargaining agreement.

Historic action: Referees are threatening to take industrial action but there will be no disruption to the finals. Credit:AAP

The NRL is opposing the application, with the matter to be decided at a Fair Work Commission hearing on Thursday morning.

If the referees are successful, the action will not affect the upcoming finals series, although there are plans to make a strong statement without disrupting the game or its stakeholders.