A TfL spokesman said: "London Underground will be attending more talks at ACAS with the RMT leadership on Tuesday, when we hope to understand the detail of the union's concerns about our staffing proposals. We will again be reassuring the unions that these proposals come with no impact on our excellent safety record, a guarantee of no compulsory redundancies and with a commitment that every station with a ticket office will continue to have one, and that all stations will continue to be staffed."