London Underground workers are to stage two fresh strikes in a row over jobs and Tube ticket office closures, threatening more travel disruption.

Members of the Rail, Maritime and Transport union (RMT) will walk out for 16 hours from 6pm on February 5 and for 15 hours from 10am on the 7th.

The action was called despite lengthy talks with LU under the chairmanship of the conciliation service Acas, which have failed to break the deadlocked row.

The RMT and Transport Salaried Staffs’ Association (TSSA) staged a 24-hour strike earlier this month which crippled Tube services.

The RMT has said further strikes will be taken in March once they are determined and agreed.

Over 3,000 station staff members were balloted for action over the impact on safety from the axing of nearly 900 front-line workers alongside the closure of Tube ticket offices.

The unions have warned that the job cuts have left safety on a “knife edge” with repeated reports of dangerous overcrowding on stations and platforms.

Union members have been banning overtime, which they say has exposed the “massive deficiencies” in station staffing.

Mick Cash, RMT general secretary, said: “RMT will not stand by while safety is compromised on London Underground off the back of cash-led cuts to staffing levels that the union has warned would have a serious, lasting and corrosive impact for staff and passengers alike. That is why our members are taking this further action.

“RMT members on the London Underground stations see day in and day out the toxic impact of the job cuts programme and they are reporting back that it is horrific.

“It has now also been shown that at management level there is agreement with the union that the cuts have been a disastrous mistake.

“With the constant overcrowding on stations and platforms it is only a matter of time before there is a major tragedy if we don’t act decisively.

“Our dispute is about taking action to haul back the cuts machine and put safety back at the top of the agenda.

“The union remains available for further serious talks.”

TSSA general secretary Manuel Cortes said: “Our negotiating team has been having talks with London Underground at Acas during the past fortnight.

“On Monday, we will be meeting with our LU workplace representatives to discuss the outcome of these discussions and decide our next steps. Until then, we will be making no further comment.”