As London Underground prepares to lay off 5% of its workforce over coming months, the Rail Maritime and Transport union (RMT) and the Transport Salaried Staffs Association (TSSA) are expected to announce a series of 24-hour strikes by Tube workers.
According to BBC News, the first is pencilled for 7 September.
Union leaders have threatened one 24-hour strike per week until London Underground withdraws its plans to axe 800 jobs and close ticket offices at 250 Tube stations across the capital.
Howard Collins, London Underground's chief operating officer, said: "It is simply not possible to go on with a situation where some ticket offices sell fewer than 10 tickets an hour. It is clear that passengers can be better served by getting staff out from behind the windows of under-used ticket offices.
"We need to change, but we will do so without compromising safety, without compulsory redundancies, and in a way that means all stations will continue to be staffed at all times and all stations with a ticket office will continue to have one. The weak mandate for strike action, which saw only around 35% of TSSA members and less than a third of RMT members voting for a walkout, should resonate with the unions' leadership."
Transport for London says sales from ticket offices are down 28% over the last four years as more people switch to the Oyster card payment system. "The changes proposed by London Underground are designed to ensure that customer service and safety remain the top priorities, that staff remain available at every station to help customers, and that all stations that currently have a ticket office service will continue to have one with opening times to reflect customer demand," it said.
"Staff will be more effectively deployed to areas of stations where they can better assist customers, whilst delivering the best possible value for fare and taxpayers. The proposed changes would mean a reduction in the total number of posts across London Underground, but will involve no compulsory redundancies, and will have no impact on the Tube's high safety standards."
Caroline Pidgeon, leader of the Liberal Democrat London Assembly Group, disagrees: "If staff numbers are severely reduced it will become far more difficult for staff to help disabled and vulnerable customers and other people who need assistance, including visitors.
"London Underground's simplistic portrayal of many ticket offices being quiet places where few tickets are actually sold overlooks the vital service and safety that staffed ticket offices provide."
Meanwhile, RMT general secretary Bob Crow said: "These shocking figures underline why RMT has told London Underground that its plan to slash 800 Tube station staff is unacceptable.
"These cuts would leave stations and platforms unstaffed and would remove the very people who are trained to deal with emergencies."