Tube strikes across the London Underground have been scheduled for 4 and 6 October.
The RMT trade union has been involved in a long-running dispute over 600 station staff cuts and claims of deteriorating working conditions over the past year.
It has also raised safety concerns over rising workloads and planned job losses across the network.
Mick Lynch, RMT general secretary, said: "TfL has had its budgets slashed but the savings made by these station staff cuts will be negatable and will lead to shortages that are unacceptable.
"This strike action will lead to the tube being shutdown and we call on Mayor Sadiq Khan to meet us urgently to discuss this matter."
Earlier this week, train drivers' union ASLEF announced two further days of strike action on 30 September and 4 October in a long-running dispute over pay and conditions.
There will also be an overtime ban across the UK rail network on 29 September and from 2 October until 6 October.
Both the RMT and ASLEF strikes will coincide with the Conservative Party Conference in Manchester and mean virtually no trains or tubes will run on 4 October, the final day of the event.