Britain's biggest rail union will today come under renewed pressure to abandon a series of strikes which have caused months of led misery for tens of thousands of commuters.
RMT members are involved in a long running dispute with rail firm Southern over the role of guards on trains between London and the south coast.
Union leaders were due to meet company executives at the conciliation service ACAS in a fresh attempt settle the row.
Southern scrapped the guards' traditional job of closing train doors at the start of the year and renamed the staff On Board Supervisors.
Rival drivers' union Aslef has already accepted the new working arrangements in a deal brokered by the TUC although a final resolution rests on the outcome of a ballot of members on Thursday.
RMT officials last week condemned the Aslef agreement as a 'shocking betrayal' and urged drivers to reject the extra duty of closing train doors.