Tube drivers are to go on strike after two unions voted to take industrial action following a claim that trust in management had broken down.
Commuters are being warned to expect more action on the Tube
About 3,500 drivers belonging to the Rail Maritime and Transport (RMT) union and Aslef are set for 24-hour walkouts on 21 February and 2 March.
They accuse London Underground (LU) of a "breakdown in industrial relations".
LU said the ballot was unreasonable and unjustified and accused the RMT of misleading its members.
'Jumping the gun'
The RMT members voted six to one in favour of striking and Aslef drivers voted four to one in support.
The union has also balloted another 5,000 Tube workers, including signallers and station staff. If they agree to a strike, it will be held on 2 March.
The unions say LU has been "jumping the gun" and tried to impose new procedures without going through the usual negotiation process.
The row covers various issues from LU's policy on signals passed at danger (Spads), to health and safety, alleged harassment and bargaining arrangements.
RMT general secretary Bob Crow said: "We never wanted this dispute. But LUL have for too long paid lip-service to the unions over our concerns regarding harassment and bullying of our members by management."
A spokesman for LU said: "There is no justification for action. Regrettably the RMT are misleading their members. LU is not imposing anything on Tube staff.
"The fact is that we launched a consultation with all our unions on new harassment, discipline and attendance procedures before Christmas. That consultation continues.
"It is unreasonable to call strikes before consultation has taken place on these issues and before the RMT have even told us their views on the proposals we are consulting about."
Aslef's general secretary Keith Norman raised hopes that strikes could be avoided when he revealed "considerable progress" had been made during talks between the two sides.
He said outstanding issues yet to be resolved included complaints about bullying and harassment of staff.