Members of the RMT on London Underground are to stage three 24-hour strikes and a week of industrial action in separate disputes over pay and plans for a night Tube, prompting Boris Johnson to call them a "disgrace".
RMT said the strikes would last from 6.30pm January 26 to 27, February 15 to 16 and February 17 to 18.
The union's station staff members will take a week of industrial action from February 7 in a separate dispute over jobs and rosters.
Leaders of the drivers' union Aslef are expected to confirm that its members will stage 24-hour strikes from 9.14pm on Wednesday January 27 followed by two further 24 hour stoppages from the same time on February 15 and February 17 in the night Tube dispute.
The London Underground (LU) has offered a four-year pay deal and said it will hire part-time drivers to staff an all-night service at weekends.
But unions have been seeking assurances for months about terms and conditions for their members.
RMT General Secretary Mick Cash said: "RMT members are furious at the bodged introduction of the Mayor’s Night Tube plans and the fact that they have been tied in with a pay deal that has left our members dangling on a string and out of pocket since April last year.
"RMT supports the principle of a properly worked out Night Tube service introduced through agreement with the unions but the abject failure to work through the detail has led to a comprehensive breakdown in the negotiations and has forced us to name a programme of further industrial action.
"This whole situation could have been avoided if London Underground, under direction from the Mayor, had dealt with the Night Tube professionally from the off instead of resorting to ultimatums and imposition."
Boris Johnson tweeted that the Night Tube had "overwhelming support" from Londoners and the deal offered to RMT members was "very fair".
To be clear - night tube has overwhelming support of Londoners, 700 more jobs, v fair pay offer, no change to working conditions = strike— Boris Johnson (@MayorofLondon) January 11, 2016
Union bosses strike re night tube a disgrace. TfL offer fair, members not consulted, now oppose part time drivers https://t.co/PAMiIY1WFt— Boris Johnson (@MayorofLondon) January 11, 2016
Cash added it was "crazy" to be imposing new rosters linked to the axing of over 800 jobs through the closure of ticket offices.
"The station staff are the eyes and ears of the Underground and hacking back their numbers represents a lethal gamble with safety that RMT will continue to fight against."
On Sunday, when the Aslef union announced meet today to discuss whether to press ahead with industrial action, Johnson said: "It is unbelievable that the leadership of Aslef should now be contemplating strike action. They were offered excellent terms and conditions for their members to deliver the night tube.
"They turned those down - without ever properly consulting their membership. They claimed - falsely - that the night tube would badly affect the "work-life balance" of staff. They held a series of strikes in pursuit of outrageous demands."
He added: "It would have been much better and quicker if the union leadership had even allowed their membership to consider the excellent offer from LU, but they seem to have succumbed to an advanced attack of Corbynitis."Suggest a correction