A train drivers’ union won’t join the planned Tube strike later this month, saying it awaits the outcome of more talks.
Three other unions – RMT, TSSA and Unite – have announced two 24-hour walkouts on 25 and 27 August.
Transport for London denied rumours its planned Night Tube service, which is at the centre of the dispute with the unions, could be delayed from its planned 12 September start date.
But bosses added the service would not be launched “at any cost”, even though it was “operationally ready”.
New demands by unions would cost £1.4 billion and lead to “significant” fare rises, it has claimed, adding “no responsible management could agree” to the demands being made by the union leaders.
A statement said the cost of what unions were asking for would be about £1.4 billion to 2023/24, increasing fares by 6.5% or scaling back modernisation plans.
Chief operating officer Steve Griffiths said: “Having previously argued that it was all about work-life balance, certain unions have now made a whole series of unaffordable demands for more pay, shorter working hours and the reversal of the modernisation of the Tube.”
RMT general secretary Mick Cash said: “Our members the length and breadth of London Underground have made it clear that they are determined to protect their work/life balance and not fall into a trap where they will be forced to wreck their home lives in order to comply with the ‘rosters from hell’ which have been drawn up to plug the staffing gaps in the night Tube plans.
“Staff are angry that their grievances are being ignored and dismissed by both the Mayor and his officials and that there has been no substantial move as of today from London Underground to make progress towards a negotiated settlement.
“That is why we have no option but to strike again. It is ridiculous that the job cuts programme for fleet, engineering and station staff is also still being bulldozed through against this background.”