Tube strike: Drivers to go on strike in December
London Underground (LU) drivers are to stage a 24-hour strike on 6 and 7 December, coinciding with a walkout by Southern rail guards.
The Rail, Maritime and Transport union said Piccadilly and Hammersmith & City line driver backed action over a breakdown in industrial relations.
Southern rail guards are due to walkout on the same days in a row over changes to the role of conductors.
LU called the strikes "premature" as there were talks scheduled for Friday.
The Rail, Maritime and Transport (RMT) general secretary Mick Cash said: "The dispute on the Hammersmith & City line is about the basic issues of protecting working conditions of our members and defending agreements from attempts to drive a coach and horses through them.
"The management are out of control and the anger at their failure to follow procedures has boiled over.
"This breakdown in industrial relations should never have been allowed to happen and, if agreements and processes had been adhered to from the off, the package of issues at the heart of the dispute could have been resolved through the joint machinery.
"In the separate dispute involving drivers on the Piccadilly line, safety is again a major factor and is tied in with the ripping-up of policies and procedures and ignoring warnings from staff."
LU's Steve Griffiths said: "The announcement of strike dates is premature given that we have pre-arranged talks planned at (arbitration service) ACAS tomorrow to discuss the RMT's concerns on the Piccadilly line, and on the Hammersmith & City line we are waiting for the RMT's response to our proposals to end that dispute."
Passengers on Southern services have suffered months of delays and disruption caused by the industrial action over the introduction of Driver Only Operated trains.
Further Southern rail strike dates:
00:01 Tuesday 6 December to 23:59 Thursday 8 December
00:01 Thursday 22 December to 23:59 Saturday 24 December
00:01 Saturday 31 December to 23:59 Monday 2 January