Dave O'Rourke, an actor from Dublin, was featured in a hard hat and begging in the street with the slogan "EU policy at work - British workers are hit hard by unlimited cheap labour".
This latest row follows:
l The suspension of Ukip member and London council candidate Andre Lampitt, featured in an election broadcast, for expressing "repellent" racist and anti-Islamic comments;
l Lizzy Vaid, who featured in the party's manifesto, pledging support for Ukip as a voter, but who turned out to be Mr Farage's aide;
l The insistence by the leader only his German wife, Kirsten, was able to work as his secretary because of the long hours involved.
Conservative backbencher Bob Neill said: "It is pretty hypocritical of Ukip. They always like to say 'we are not part of the political establishment', they like to claim they are the party of ordinary people. They are using a trick most other parties stopped using long ago because they get found out doing it." But Patrick O'Flynn, Ukip's director of communications, said: "It is nonsense for the Conservative Party to try and depict this as anything out of the ordinary. For example, the people depicted in the Conservatives' 'You paid the taxes ..." campaign under William Hague were actors."