The UK Rail, Maritime and Transport (RMT) union has offered binding arbitration on the use of Tube station ticket offices in advance of ACAS talks.
At the talks, the RMT said that it will offer binding arbitration on London Underground's figure of 30 ticket sales an hour to guarantee the retention of a ticket office.
The union stated that watchdog organisation London Travel Watch would have given a guideline of a minimum of 12 tickets an hour to maintain viability.
The union has rejected management proposals for a "meaningless" safety review, which it believes will make no difference to the government's plans to cut staffing levels.
The fourth 24-hour RMT strike action over safe tube staffing levels is expected to go ahead from 7pm on 28 November until 7pm on 29 November.
