Up to 11,000 transport union members are to be balloted on strike action over pensions.
The Rail, Maritime and Transport Union (RMT) believes that the pension rights of members of the Transport for London Pension Fund who are forced to leave their jobs through ill-health will be undermined if proposed changes go ahead.
The ballot covers all those members working for companies covered by the Transport for London Pension Fund and includes all RMT members at London Underground, Transport for London, Metronet , Tubelines, Cubic Transportation and EDF Energy.
Currently, an ill-health pension is granted to a worker in the Transport for London Pension Fund if ill-health makes them unfit to work.
The proposals would see ill-health pensions split into two parts: a basic pension and an additional ill-health supplement.
Anyone capable of earning an income, regardless of how small, would probably not qualify for, or retain, an ill-health pension.
Bob Crow, RMT general secretary, said: “The employers backed away when we threatened strike action last September, and these changes are just as unacceptable now as they were then.
“Rather than launching this attack on employees who suffer ill-health the trustees should simply scrap the fund rule that allows annual review of ill-health pensions,” Crow said.
The ballot will be concluded on 24 July.