Parts of London's underground, known as the Tube, will be shut for two days this week, after transport union leaders announced a strike on Monday.
The National Union of Rail, Maritime and Transport Workers (RMT) said workers will be encouraged to walk off the job on Tuesday and Thursday for 24 hours each day.
The action comes amid an ongoing labor dispute, after the union called off planned strikes last month to allow talks to continue.
Transport for London (TfL) confirmed that strikes were planned by "some Tube drivers," saying that while some lines will close, others are expected to remain open and operating.
"Despite our best efforts in ACAS talks, TfL have failed to provide assurances on our members deeply held concerns around fatigue, reduced flexibility, shift lengths and the impact these proposals could have in a safety-critical role like tube driving," RMT wrote on its X account.
