London's commuters and businesses are facing a fresh wave of travel chaos because of a series of crippling strikes over pay and plans for a night Tube.
Members of the Rail, Maritime and Transport union (RMT), Aslef and Unite will walk out for 24 hours from the evenings of January 26, February 15 and February 17, bringing services to a halt.
The RMT's station staff members will take a week of industrial action from February 7 in a separate dispute over jobs and rosters.
LU has offered a four-year pay deal and said it will hire part-time drivers to staff an all-night service at weekends.
Union leaders attacked LU for "tying" the pay deal to the night Tube, saying their members have been out of pocket since last year.
RMT general secretary Mick Cash said: "RMT members are furious at the bodged introduction of the Mayor's night Tube plans and the fact that they have been tied in with a pay deal that has left our members dangling on a string and out of pocket since April last year.
"RMT supports the principle of a properly worked out night Tube service, introduced through agreement with the unions, but the abject failure to work through the detail has led to a comprehensive breakdown in the negotiations and has forced us to name a programme of further industrial action."
Aslef's London district organiser, Finn Brennan, said: "We genuinely regret the inconvenience that will be caused but the behaviour of London Underground's senior management team have left us with no other choice.
"Our negotiating team last met London Underground at Acas on November 10 and since then they have refused to talk to us despite repeated requests. Our members have been extremely patient, they have waited for more than three and half years for promised talks on improving work-life balance.
"There is still no indication when they will receive the pay rise that was due last April."
Steve Griffiths, LU's chief operating officer, said the service will not run if the strikes go ahead.
He told the Press Association that LU will press ahead with recruiting part-time drivers to staff an all-night Tube and will be sifting through the 6,000 applications already received.
"The unions' position is absurd and detached from the real world," he said.
"Apparently, above-inflation pay rises, the creation of 700 more Tube jobs and the total protection of the work-life balance of existing staff are grounds for strikes.
"The truth is that they expect our customers to pay for their excessive demands for even more money, fewer hours and a four-day week. No employer could allow this and strike action will change nothing. There is no more money.
"This is precisely what the unions have asked for, making their call for strikes even more astonishing."
London Mayor Boris Johnson said: "The decision to strike has been orchestrated by union barons without ever properly consulting their members. It is an absolute disgrace.
"Today's decision to strike makes it abundantly clear that the union leadership is hell bent on preventing not just their own members from doing these jobs but anyone else from working the night Tube as well.
"These strikes are absurd. They will hit the travelling public, business and hard-working Tube staff, many of whom clearly don't believe in this nonsense. Ultimately it will do nothing to prevent the advent of the night Tube."
James Sproule, of the Institute of Directors, said: "Business leaders and ordinary workers in London will be shaking their heads in disbelief that they are facing yet more public transport chaos.
"Instead of getting on with putting their business plans for 2016 into action, our members now have to worry about how their staff are going to get into work on the three days of industrial action. In a dynamic metropolis like London, which relies on millions of workers being able to travel into the city every day, these stoppages are completely unacceptable."
Transport Secretary Patrick McLaughlin said: "Threatening disruption for Londoners so union fat cats can enjoy a four day week is selfish and irresponsible. A 24-hour Tube will create jobs and allow a major economic boost for London - it's an idea whose time has come. The unions want to hold back progress for a set of totally unreasonable demands."