A new bid to end the Tube strikes that threaten to disrupt travel each weekend before Christmas was being made on Tuesday.
Talks were resuming at the conciliation service Acas between the RMT union and Transport for London after two rounds of action over the way the Night Tube has been restarted.
The RMT claimed that its offer to suspend strike action was rejected by TfL last Thursday – and warned that the dispute would soon cost TfL more in lost fares than it would to resolve.
Drivers belonging to the RMT are due to walk out on Friday and Saturday night, causing a reduction in services from about 7pm on both evenings and reducing the number of Night Tube trains that run after midnight each night.
A woman passenger was taken to hospital after falling onto the Central line tracks at Tottenham Court Road station before 1am on Saturday in what was reported as being linked to overcrowding on the platforms as a result of fewer trains.
TfL said it was initially thought the fall was related to a medical incident, but admitted there were severe delays on the Central line at the time and passengers were regularly being advised to move along the platforms.
RMT General Secretary Mick Lynch said: “RMT has again agreed to meet at Acas today but the ball is firmly in London Underground’s court. They need to sort themselves out and stop the posturing because this dispute is eminently sortable.
“The cost of meeting our offer is, in real terms, minimal, whereas if they continue with their current line they will soon have lost more in passenger fares than it would take to train up 200 Night Tube drivers.”
The dispute centres on TfL’s decision to scrap the Night Tube posts and incorporate the 200 drivers, all of whom worked part-time, within the “day” Tube workforce.
All drivers on the Night Tube lines are then required to work an occasional Night Tube shift – about four a year, according to TfL.
Strike action began with a 24-hour walkout on November 26 on five lines, and will continue with drivers refusing to book in for shifts on the Victoria and Central lines from 830pm each Friday and Saturday until December 18.
On that date – the last Saturday before Christmas - another 24-hour strike is planned on those lines plus the Northern, Piccadilly and Jubilee, which have yet to restart Night Tube services.
The RMT estimated TfL was losing almost £750,000 a day in lost fares revenue from the strikes – while TfL says it would cost £3.2m to train a new contingent of part-time Night Tube drivers.
The RMT said it offered last week to suspend the strike and work the disputed Night Tube shifts until new drivers could be recruited and trained, as long as TfL returned to a 2016 agreement that no driver would be forced to work night shifts.
But TfL says the RMT’s proposal to recruit and train a new cohort of Night Tube drivers would delay the reopening of the Night Tube on the Northern, Piccadilly and Jubilee lines until 2023.
TfL says a voluntary system would not work for the Night Tube as it needs to be sure it has enough drivers willing to work each weekend. It said Aslef, the other main Tube drivers’ union, accepted the new system in May.
A TfL spokeswoman said: "We welcome further talks with the RMT so that we can seek to resolve this dispute and avoid further disruption at such a pivotal time for London’s recovery.”