Further tube strikes are set to hit London next month if Transport for London's negotiations fail with the unions.
RMT has today (January 12) announced that a new phase of industrial action will go ahead on February 6 if its "reasonable demands on station staffing and safety" are not met.
Mick Cash, RMT general secretary, said: "RMT members have shown this week that they 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."
London crippled by January strikes which saw millions stranded
He added: "That is why our members have been forced to take this 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."
The union argued that cuts of more than 800 staff members have already proven to be "disastrous" as TfL confirm it is looking to recruit 200 staff members.
But earlier this week, City Hall Labour party said the strikes were "premature" given London underground were reviewing staffing levels.
Despite the outrage of commuters, the Mayor and Prime Minister Teresa May during the January strikes , RMT has put aside balloting for further action and the union's executive himself has said it will ahead if negotiations do not come to a conclusion.
Rail unions also confirmed that guards on Southern Rail will be taking further strike action in the on-going fight for safety and the retention of a second member of staff on the company’s services.
Members will strike again for 24 hours on January 23.
Transport for London has been approached for comment.
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