Around 2,000 of London Underground staff are set to vote on Wednesday whether to strike in a dispute over jobs.
Members of the Rail, Maritime and Transport union (RMT) claim that job cuts are being “smuggled in” over a transformation programme.
The results will be known around mid-July, the RMT has further warned that train operators could strike in a dispute over pensions also.
RMT general secretary Mick Cash said, “Staff across London Underground are furious at the attempts to smuggle in a creeping programme of cuts and privatisation under the cloak of the transformation programme.
“RMT on London Underground is now on a war footing and it’s about time the management, and the London Mayor, woke up and took notice.
“If we are forced by their inaction to escalate the dispute then that is exactly, we will do.”