Rail workers are being balloted on plans to hold their first national strike in 25 years.
The move by the Rail, Maritime and Transport union comes amid a pensions row, with the Pensions Regulator warning train operators face a black hole of up to £7.5billion.
The RMT claims the Government and train firms have failed to guarantee current arrangements will not be undermined.
And an RMT letter to Transport Secretary Chris Grayling states it will take the “necessary action” for workers.
General secretary Mick Cash said: “If it takes the first national rail strike in a generation to defend our members’ pensions, then so be it.
“We will not tolerate a position where Chris Grayling and the train companies are playing fast and loose with rail pension rights and RMT members will not be left to pay the price for the collapsing chaos of the rail franchising system.
“We have made it crystal clear that this union will resist any attack on our members’ future pension rights either as a result of Government policy or greedy employers wanting to prop up their profits within the failed private franchise model.
“Any such attack will be met with a campaign of co-ordinated industrial action across the rail industry to defend pensions and in the absence of a satisfactory response from Government and the train operators, that is where we are now heading," he added.
The Department for Transport said: “The threat of a national strike by the RMT underlines their total disregard for passengers.”
The national dispute in 1994, involved staff at Network Rail predecessor Railtrack.
Two-thirds of trains were axed over strike days.
