RMT warns of more Tube strikes over ticket office closures
Strike action will be escalated by London Underground (LU) workers from 6 February unless a dispute over ticket office closures can be resolved, a union has warned.
The Rail, Maritime and Transport (RMT) union said a ban on overtime would also continue.
It comes days after a 24-hour strike brought disruption to commuters.
Conciliation service Acas has said fresh talks will be held between LU and the RMT on Monday.
The Transport Salaried Staffs' Association (TSSA) will also join the talks.
The unions are campaigning to have jobs reinstated and ticket offices reopened, saying cuts agreed by former London mayor Boris Johnson have gone too far.
Monday's walkout led to the closure of most central London Tube stations, but TfL managed to provide some services on 10 of its 11 Tube lines.
Current London mayor Sadiq Khan called the strike "completely unnecessary".
Labour leader Jeremy Corbyn also waded into the dispute on Thursday, calling on the mayor to reopen ticket offices in some Tube stations.
Speaking to BBC London's political editor Tim Donovan, he said: "I do think there's a need to have a ticket office, particularly in the big interchange stations.
"That surely can be discussed and negotiated."
Mr Corbyn also refused to condemn union members and refused to say whether he would be prepared to join striking underground workers on a picket line.
He said: "I will urge them to get around the table as quickly as possible, and TfL to do the same."
TfL said 200 new jobs are being created and more may be created over time.
Steve Griffiths, LU's chief operating officer, said: "We look forward to resuming talks at ACAS on Monday in order to make progress towards resolving this dispute."