Union leaders were making a last ditch attempt to head off a strike by London Underground workers by seeking talks with the capital’s mayor.
Bob Crow and Manuel Cortes, general secretaries of the RMT and TSSA unions, went to City Hall to try to confront Boris Johnson.
Tube services will start to be disrupted later today after talks failed to resolve a row over the closure of Tube ticket offices.
Members of the Rail, Maritime and Transport union (RMT) and the Transport Salaried Staffs Association (TSSA) will walk out for 48 hours from 9pm and again at the same time next week.
Transport for London warned that services will be hit from this evening until Friday morning, causing travel chaos for passengers.
Mr Crow said: “We have exchanged letters with Boris Johnson and it’s now time to meet face to face – if he won’t come to us then we are showing our willingness to engage by travelling to him. This dispute is too important for London for anyone to retreat into their bunker.
“We are making it clear again today that if Boris Johnson lifts the threat to jobs we will suspend the action to allow for fresh talks from a clean slate. It is not too late for Boris to take up that fair and reasonable offer and we are at City Hall to make it happen.”
Mr Cortes added: “It is time for Boris to stop playing politics with the Tube. He may impress the right wing of the Tory Party by picking a fight with us but he is doing no favours to the travelling public.
“They want what we want. A properly staffed, safe and secure tube network.”
London mayor Boris Johnson described the strike as ``totally pointless'' and admitted that he had not spoken directly to Mr Crow since ``a few years ago''.
He said: “I can’t possibly sit down and talk to Bob Crow when he is not negotiating with our team, with the London Underground staff and they are threatening a totally pointless and, definitely will be, debilitating strike.”
Appearing on LBC 97.3, he said: “There are no compulsory redundancies here. Nobody is being forced out and actually we have so far had more than 1,000 expressions of interest in voluntary redundancies, so we are already there.”