A striking union has branded the Night Tube “a gimmick” as drivers prepare to walk out over disputes around the service.

Transport Salaried Staffs’ Association (TSSA), the fourth of the unions to join the second walk out in just a month, has blamed the London Mayor for the strike, which will cause the entire London network to shut down from 6.30pm this evening until Friday morning.

“The Night Tube was a gimmick when Boris Johnson first announced it and it still remains a gimmick today,” said Manuel Cortes, leader of the rail union, after the breakdown of talks at mediators ACAS.

Mr Cortes accused Boris Johnson of not being able to afford the service, saying “he is now gambling with the health and safety of our members”.

While the dispute has centered so far around pay, as well as working conditions, Mr Cortes said the issue was not about pay but the work/life balance of his members, as well as safety issues with staffing levels on the Night Tube.

“There are a number of stations where there will be one member of staff on duty during the middle of the night,” he said.

“With crowds of potential drunks to deal with, we think that could be an accident waiting to happen.”

Tube union RMT, who are striking today with TSSA, Unite and ASLEF, announced today that staff working for Tube Lines are to be balloted for both strike action and action short of a strike over pay and 24 hour working.

“Tube Lines staff have been offered a deal over the next two years on pay and 24 hour running which mirrors that on offer to the rest of the LU workforce,” saud RMT general secretary Mick Cash.

“It is as unacceptable on Tube Lines as it is across the rest of the combine and as a result these essential maintenance staff will now be balloted for both strike action and action short of a strike.

“RMT is preparing for that ballot now and the union remains available for talks.”

The Tube Lines staff maintain the Piccadilly, Northern and Jubilee Lines. Their operations are owned by London Underground, but they remain a separate bargaining unit for industrial relations purposes.

Drivers will have the same number of weekends off as now and no one will be asked to work more hours than they do today. Everybody will remain entitled to two days off in seven. Annual leave will remain at 43 days for a train driver and 52 days for station staff,” said London Underground managing director Nick Brown.

“The unions rejected this fair offer outright and instead demanded more money, the hiring of even more staff – including for ticket offices that customers no longer use – and a 32 hour, four day week. No employer can afford to meet those sorts of demands.

“We continue to urge them to call off the strike, put the new offer to their members and not subject Londoners to further unnecessary disruption. We remain available for talks at any time.”

Plan your journey by heading to tfl.gov.uk/plan-a-journey/