Tube drivers are to hold a series of 24 hour strikes, including one on Boxing Day, over pay.
The ASLEF user balloted its 2,200 members over a demand for triple pay and a day off lieu of working on the bank holiday.
Three additional strikes will be held on 16th January, 3rd and 13th February.
The union announced in November that it was balloting members after it was unable to reach agreement with London Underground over “adequate compensation” for working on the Bank Holiday.
In a statement the union said: “The whole dispute has been about seeking equitable quality time off for our members but recognising those who do operate the service may need to be incentivised.”
Howard Collins, London Underground’s Chief Operating Officer, said: “London Underground has a long-standing agreement with all of its trade unions which cover staff working arrangements on bank holidays, and Boxing Day is included in that agreement”
Collins said the strikes “will not achieve anything” and called on the union “to resolve this matter through discussions.”