Thousands of London Underground workers are to start voting on whether to strike in a dispute over jobs.
Members of the RMT union are being balloted from Wednesday over claims that cuts are being "smuggled in" under a so-called transformation programme.
Around 2,000 staff will be balloted, including those working in engineering, signals, electrical, track and control centres. The result will be known in mid-July.
The union has also warned of industrial action against train operators in a dispute over pensions.