A second trade union has threatened industrial action on the Tube in a dispute over pay.
The Transport Salaried Staffs’ Association (TSSA) said it is planning to ballot its London Underground members after rejecting a pay offer.
The union said that after months of talks the offer was a pay rise of 5% and a plan to freeze pay bands and salary ranges.
TSSA general secretary, Maryam Eslamdoust said: “Our members on London Underground are deeply unhappy at this sub-standard and simply unrealistic offer.
“We will now move to a ballot for industrial action, raising the very real prospect of a crippling strike on the Tube.
“If this is to be avoided London Underground must come back to the table with an offer which takes account of the ongoing cost-of-living crisis.
“The offer, as it stands, really amounts to a pay cut for our members who do so much to keep London moving every day of the year.
“It fails to address the fact inflation has been sky high in recent times and other components of the proposed deal, relating to salary bands, are unacceptable.
“Our door is always open for further talks but it’s time for London Underground to get real.”
TSSA is the biggest trade union in Transport for London representing thousands of staff in TfL offices and stations, bus operations, London Underground, TfL Rail, and the Overground.It is unclear when the ballot will open and when a result is expected.
But it comes as commuters already face a week of misery on the Tube next week as members of the Rail, Maritime and Transport union who work on the Tube take industrial action over pay.
The RMT action is expected to severely disrupt services from Monday to Thursday.
Talks were taking place on Friday in the hope that the strike action could be averted.