London Underground train drivers are to go on strike over pay and conditions, a union has confirmed.
Some 95% of ASLEF drivers voted for the action “to achieve a fair deal on pay and conditions”.
The ballot included equally high support from engineering staff and test train drivers.
ASLEF said it “will not hesitate to call action” if London Underground failed to “make an improved offer to settle this dispute”.
The union has not announced the dates of a strike, which can be held anytime in the next six months.
Members of the Rail, Maritime and Transport union were balloted last week on strike action as part of a pay dispute and the results are due at the end of March.
London Underground said it was waiting to hear officially from ASLEF before it commented.
Tom Edwards, BBC London Transport correspondent
Staff on the Tube are coming to the end of a four-year pay deal, so relatively speaking, there has not been a lot of tube-wide industrial action.
But this is the big one, as it is over pay. The problem is Transport for London does not have a lot of wriggle room.
It has lost its government grant and is paying for the mayor’s fares freeze as well as the loss of Crossrail revenue.
It is not yet clear what action the unions will take – with the coronavirus pandemic they may decide the timing is not right, or they may try and do it before the mayoral elections and force candidates into commitments.