The union is to ballot members for industrial action after TFL banned staff leave for the duration of the Olympics.
It is also in dispute with London Underground “over a failure to reach an agreement on Olympics recognition and reward payments for all LU staff.”
In a statement the RMT says the holiday ban “will make life impossible for many staff” who have family commitments.
RMT General Secretary Bob Crow said: “RMT reiterates our stance that all grades of transport employees are entitled to a decent financial reward for their efforts transporting huge numbers of passengers during the Olympics and are entitled to take leave during the summer.
“Working conditions and important agreements should not and need not be attacked in order to facilitate Olympic running.”
