Tube staff have voted in favour of strike action proposed by three transport unions over a jobs and conditions row.
Metronet went into administration after a projected £2bn overspend
The RMT Union and Transport Salaried Staffs' Association and Unite held ballots over job losses faced by staff employed by maintenance firm Metronet.
Metronet, which is responsible for the upkeep of nine Tube lines, went into administration in July.
Its administrators have until Wednesday for assuring workers' jobs, RMT said.
If the talks fail the unions will declare a date for strike action on Thursday.
Metronet was one of two private infrastructure companies set up under London Underground's public-private partnership (PPP) initiative.
The unions claim that Metronet has not given job and conditions guarantees since going into administration after projecting an overspend of £2bn by 2010.
Workers may also face forced transfers and pension cutbacks, the unions added.
RMT general secretary Bob Crow said: "Our members have said with a single, united voice that they are not prepared to be made to pay for the failure of the PPP with their jobs, conditions or pensions.
General secretary for Transport Salaried Staffs' Association (TSSA), Gerry Doherty, said: "Metronet shareholders may be able to walk away from this PPP fiasco but it is our members who are being asked to pick up the bill with lost jobs, transfers and pension cutbacks."
Workers voted by 1,369 to 70 in favour of industrial action.
A Transport for London (TfL) spokeswoman said the vote for strike action was "completely unnecessary".
"It is particularly unreasonable at a time when administrators are working to ensure the stability of Metronet following the company's collapse," she added.
"There are agreed channels for discussion on these issues and the trade unions should use them, rather than call for strike action."
TfL has asked the unions to work with Metronet's administrators "to enable them to get the company on a stable footing and out of administration as soon as possible".