More than 10,000 London Underground workers are to be re-balloted for strikes in dispute over jobs and pay.
The Rail and Maritime Transport Workers union (RMT) said that its members working across the Tube network, as well as Transport for London, will vote in the next few weeks on whether to launch a campaign of industrial action.
The rerun of the voting follows a legal challenge by London Underground last month against a ballot that showed a five-to-one majority in favour of strikes.
The union claimed as many as 3,000 jobs were under threat, and many may be cut through compulsory redundancy.
RMT general secretary Bob Crow said: "Our members are furious that a democratic vote for action just a month ago was sabotaged by a shameful legal challenge aimed at undermining the internal democracy of our trade union."
"Despite the management's diversionary tactics, it remains the case that, after months of stonewalling, London Underground has tabled what is at best a five-year pay freeze, which it knows full well is totally unacceptable to RMT and its members," he added.
London Underground said it was "disappointed" the union had chosen to re-ballot.
"The RMT has chosen to ballot its members rather than negotiate using agreed procedures, but we believe these issues can be resolved without the need for industrial action," a spokeswoman told Personnel Today.
"We seek a further fair and affordable long-term agreement that seeks to provide stability for our staff in a period of great financial uncertainty. However, the RMT have yet to engage in any meaningful negotiations."