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Publication Date: March 26 2012
RMT also confirmed that it has referred the matter as a formal complaint to the Electoral Commission.
The "Not Ken Again" poster began appearing in London in early March.
A spokesman for RMT said:
"Our opinion is that this poster falsely portrays Bob Crow and RMT as part of some corrupt, venal, scandalous and wasteful group of cronies associated with Ken Livingstone.
"It also seems to portray Bob Crow and RMT as supporters of Ken Livingstone when the truth is that Bob Crow has not supported Mr Livingstone's campaign as a Labour Candidate for Mayor, is not a member or supporter of the Labour Party and RMT is not affiliated to the Labour Party.
"As General Secretary of RMT Bob Crow is wholly engaged in his duties in representing the interests of RMT members. The allegations contained in this poster infer that that is not the case and it has a negative impact upon Bob Crow's reputation among both his membership and with the public at large.
"RMT has made it clear that we will have no hesitation in taking swift and decisive action against any individual or organisation that makes false and damaging allegations against the union and its officials."