Union leaders today renewed their call for last-ditch talks in a bid to avert two 48-hour strikes by London Underground workers which threaten disruption from next week.
The Rail Maritime and Transport union warned that planned walkouts by its members employed by Tube Lines from Wednesday June 23 and again from Wednesday July 14 will "severely" hit Tube services.
The work of Tube Lines is being taken over by Transport for London at the end of the month but the union is in dispute over jobs, pay and conditions.
RMT general secretary Bob Crow said London Mayor Boris Johnson should "get out of his bunker" and hold talks, adding: "As the clock ticks down, the mayor cannot wash his hands of this issue and should show some leadership and agree to direct talks with RMT."
A TfL spokesman said: "The RMT have time and again called for Tube Lines' work to come back under public control, and that is what we are working to achieve. Furthermore this is an existing dispute about pay and conditions and not about the proposed transfer of Tube Lines to TfL.
"We strongly urge RMT leadership to call off the threatened strike action and to enter proper dialogue with us after our acquisition of Tube Lines."
RMT members on Docklands Light Railway are planning to strike for three days from next Wednesday in a separate row over pay.
A spokesman for Mr Johnson said: "The RMT are well aware that the mayor has made it clear he will not meet with unions threatening strike action on the capital.
"Rather than threatening disruption the RMT should call off their strike action and hold talks with TfL once their purchase of Tube Lines has been completed."