London Underground workers begin 24-hour strike
Unions are expecting the strike to have a "massive" impact on services
London Underground passengers have been advised to find alternative routes in London as the first in a series of 24-hour strikes begins.
Maintenance staff walked out at 1700 BST and drivers, signallers and station staff stopped working at 2100 BST.
They are unhappy about plans to scrap 800 jobs in ticket offices and say security could be at risk.
There have been minor delays on the District, Central and Circle lines and the Bakerloo line is part suspended.
BBC London's transport correspondent Tom Edwards said the level of service would depend on how many people turned up for work and how many managers there were available to replace them.
"Comparing it to the last strike, which involved one union and was over pay, when there was severe disruption, this time there are two unions so I think we can expect a skeleton service at best," he said.
The Rail Maritime and Transport (RMT) and the Transport Salaried Staffs' Association (TSSA) unions are fighting plans to cut ticket office staffing levels, claiming security could be compromised for passengers.
But London Underground (LU) has insisted the plans would mean all stations would still be staffed and has pledged there will be no compulsory redundancies.
In a separate dispute, up to 200 Jubilee and Northern line maintenance staff employed by Alstom-Metro began a separate 24-hour strike at 1900 BST on Sunday after rejecting an "insulting", sub-inflation pay offer.
The RMT has said it expects the impact of the strikes to be "massive".
A spokesman for the union said: "You can't run a railway without 10,000 workers.
"The level of service will depend on how many managers LU can get to stand in but there are safety implications of doing this."
Passengers have been warned to expect disruption from late afternoon on Monday and for most of Tuesday.
A Transport for London (TfL) spokesman said it expects to be able to provide a 50% service on some lines and 25% on others, but it cannot say which and would be reviewing the situation hour-by-hour.
He said: "Realistically people will experience difficulties this evening after peak going-home time and tomorrow."
People have been advised to find an alternative way of travelling with an extra 100 buses and 10,000 more passenger journeys on Thames riverboat services being laid on.Lapsed licences
Some taxi ranks will be marshalled and escorted bike rides will be operating during the strike.
Meanwhile the RMT has accused Tube bosses of playing "fast and loose" with safety as it claimed a circular had been sent to staff seeking volunteers to help run services during the strike.
According to the union the note, signed by LU's managing director Mike Brown, said no operational licence was needed if people volunteered to support staff turning up for work, adding that lapsed licences could be renewed.
RMT General Secretary Bob Crow said: "Sending out a few volunteers without the necessary operational licences and training to try and run a few trains is a disaster waiting to happen."
Denying the allegations TfL said it would never do anything to compromise safety on the Underground.