UKIP has clashed with the Tories over its use of an Irish actor on an election poster about British workers being hit by foreign labour.
Tory vice-chairman Bob Neill accused UKIP of being "hypocritical" for not using "ordinary people" in their £1.5m poster campaign.
On Wednesday, UKIP leader Nigel Farage suggested his party did not use actors in its campaign literature.
But on Friday, UKIP said the use of actors was "totally standard practice".
The poster, unveiled this week as the Eurosceptic party launched its campaign ahead of elections on 22 May, features a builder in a high-visibility jacket and a hard hat begging on the street next to the slogans "EU policy at work" and "British workers are hit hard by unlimited cheap labour".
The man featured on the poster is actor Dave O'Rourke, who moved to the UK a decade ago.
Mr O'Rourke's nationality appears to have been revealed by blogger Steve Griffin, who is thought to be a friend of the actor.
It provoked a flurry of criticism and jokes on Twitter, with tweets asking why UKIP could not have found a British worker to be the face of their anti-EU immigration campaign.
Others pointed out that Irish citizens have been free to enter Britain since before it joined the EU - thanks to longstanding agreements between the two countries - and are treated as British citizens for tax and benefit purposes.
Irish citizens would continue to have free access to the British job market if Britain left the EU.
Mr Neill, the Conservative MP for Bromley and Chislehurst, said: "I think 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. As far as I am aware, we always use genuine people in our adverts."
But UKIP director of communications Patrick O'Flynn highlighted the Conservatives' use of actors when William Hague led the party.
He said: "The vast majority of people used in political poster campaigns are actors. It is totally standard practice.
"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.
"So, Bob Neill needs to go and berate the foreign secretary if he really thinks there is anything wrong with this. Of course he won't because this is pure Tory party humbug.
"I would suggest that the only substantive difference between our poster campaign and Mr Hague's is that ours is proving popular and successful while his was followed by a landslide defeat."
On Wednesday it was revealed that UKIP had portrayed an aide to Mr Farage as a "voter" in the party's new manifesto.
Defending the use of her photo, Mr Farage said: "Most parties use actors. We use Ukippers."
UKIP has suspended a council candidate featured in its latest election broadcast for sharing "repellent" opinions on Twitter.
Posts put up by builder Andre Lampitt had expressed "extreme racist views", a source said.
Mr Farage, who has launched an investigation into his selection, said he was "very angry".
Mr Lampitt featured in an election broadcast on Wednesday, expressing his views on the effects of immigration.
Shown wearing a hard hat, he complained that "since the lads from Eastern Europe" had arrived in the UK and undercut him, he had found it a "real struggle" to provide for his family.
But after being made aware of posts he previously made on Twitter, officials acted swiftly against Mr Lampitt, who is seeking to become a councillor in Merton, south London.