There are four separate strikes planned between 19 June and 1 July 2011 on the London Underground, Britain's Rail Maritime and Transport union (RMT) said on Thursday.
The first strike will take place between 2001 GMT on 19 June and 0200 GMT on 20 June, further action is set to take place between:
- 2100 GMT on 27 June and 1159 GMT on 28 June;
- 1200 GMT on 29 June and 1159 GMT on 30 June;
- 1200 GMT and 2100 GMT on 1 July.
The industrial action is set to hit commuters and tourists alike as services will be disrupted during peak hours.
The strikes are part of an on-going dispute over the dismissal of Northern Line driver Arwyn Thomas.
The union's general secretary Bob Crow said: "RMT has made every possible effort to get Arwyn Thomas back to work and it is the intransigence of LU management, who have dragged their heels and failed to reach agreement over the past month that has left us with no choice to put this strike action on.
"This is a clear cut case of victimisation and RMT calls on London Underground once again to stop the delaying tactics, and the continuing waste of hundreds of thousands of pounds that they have thrown at this case, and get Arwyn Thomas back to work."
A Transport for London (TfL) spokesman said it would "respond appropriately to the tribunal's finding", and said the strike action had been backed by only 29 per cent of union members.
"It is completely mystifying that, having agreed with London Underground that the tribunal process should take its course, the RMT leadership is now threatening strike action again," a spokesman said.
"We remain determined to improve the industrial relations climate and have been working with the RMT to ensure a jointly sponsored independent overview of disputes takes place.
"This recent positive engagement makes it all the more incredible for the RMT leadership to threaten Londoners with strike action once again, particularly as it was backed by just 29 per cent of its members."
The spokesman said TfL would "respond appropriately to the tribunal's finding".