The Twitter account of the union at the centre of the rail workers dispute has added more than 60,000 new followers in the past week.
But the Rail, Maritime and Transport union (RMT) said not all the new followers will be supporters.
The @RMTunion account, which is 13 years old, has attracted huge interest since the row over jobs, pay and conditions flared.
The RMT said: “Not all those followers will support us, or trade unions. However, we must build on this groundswell of support and reject the Tory race to the bottom.”
Meanwhile, an analysis of Google search data reveals that searches for “join union” have increased to their highest level in over a year.
The study, by recruitment experts Workello, showed that searches for the phrase have increased threefold in the past week.
The data also showed that searches for “how to strike” have increased by 135% since the rail strikes began.
Unite general secretary Sharon Graham said: “More workers are joining unions because they can see it is the only way to fight back against the attacks on their living standards.
“The system is rigged in favour of profiteering corporates who get fat by driving up inflation and holding down wages, and politicians are unwilling or unable or to stop it. Unions are now setting the agenda.”
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