OSLO, Oct 22 (Reuters) - One of Norway's two labour unions for oil service workers struck a wage deal with subcontractors to the country's oil industry, while a second union broke off talks, union officials said on Thursday.

Industri Energi, the largest of the two labour unions involved in negotiations, said it had agreed to a deal, while the smaller Safe union said it had broken off talks and would face mandatory mediation later this year.

Members of Safe are not permitted to strike at this point, but could do so if the next round of talks also fails to bring agreement. (Reporting by Terje Solsvik and Nerijus Adomaitis; Editing by Jacqueline Wong)