The Rail Maritime and Transport union (RMT) today warned that London Underground bosses could put passengers' safety at risk by using undertrained staff during a Tube strike.
Thousands of members of the RMT and the Transport Salaried Staffs Association (TSSA) are set to walk out for 24 hours from 7pm tomorrow in a row over 800 job cuts.
Bob Crow, RMT general secretary, said: "We have been leaked information that managers have been given two days training on key deep safety and emergency procedures that the regulations say require six weeks of intensive instruction.
"That is an outrageous case of playing fast and loose with life or death safety procedures and shows that there is no corner that London Underground won't cut to try and run skeleton services regardless of the risks to the public.
"Instead of playing dangerous games down the deep tube tunnels the managers responsible for this lethal gamble with safety should be engaging in proper talks with the unions to resolve the issues at the heart of this dispute."
Nobody from Transport for London (TfL) was immediately available for comment.
Transport bosses are laying on more than 100 extra buses, increasing capacity for more than 10,000 more journeys on the river, organising marshalled taxi ranks and delaying or curtailing planned roadworks.
Volunteers will also be positioned at Tube, bus and rail stations to help commuters with their journeys and provide maps and other information, and people who own a bike are being encouraged to cycle to work.
TfL said London Underground ran a third of its normal services during a walkout last month, carrying more than a million people.
London Underground said the deep tube stations that are kept open will be staffed with a combination of the required number of licensed supervisors and station assistants.
A spokesman said: "The RMT are, once again, scaremongering. We have asked managers and staff to volunteer to staff stations and provide information to the public about alternative services.
"However, we would never ask anyone to carry out safety-critical roles unless they held the relevant licence."