Hundreds of London Underground maintenance workers are to be balloted for strikes over a "complete breakdown" in industrial relations.
Members of the Rail Maritime and Transport union will vote in the coming weeks, raising the threat of industrial action on the Tube in the run up to Christmas.
RMT general secretary Bob Crow said: "The management's attempt to bulldoze through unilateral changes to working practices, staffing levels and procedures is a clear attack on the fleet core work agreement and is completely unacceptable to RMT members.
"The union is disgusted by London Underground's attacks on the jobs and working conditions of our fleet maintenance members. RMT firmly opposes the company's plans to reduce maintenance frequencies, cut jobs and replace skilled staff with unreliable automated processes."
Drivers on the Jubilee line are planning two 24-hour strikes in a row over working conditions and claims of bullying, threatening disruption after the Easter break.
Members of the Rail Maritime and Transport union and Aslef on the Jubilee line are set to walk out next Tuesday and again on May 2nd.
The drivers voted overwhelmingly for industrial action, claiming bullying of staff and an "appalling decline" in the standard of working conditions which unions said have led to a breakdown in industrial relations.
Talks will be held at the conciliation service Acas to try to avert the strikes.
"There has been a cynical attempt to trivialise the issues at the heart of this dispute, but the fact is they amount to a systematic undermining of working conditions and staff morale on a Tube line that faces constant pressure from frequent breakdowns and failures, and where drivers are in the front line of trying to maintain both an effective service and passenger safety.
"Their reward has been attack after attack on working conditions and on both individuals and the drivers as a group of staff."