UKIP has accused the Conservative party of running a "morally reprehensible" smear campaign by trawling through potential councillors' Twitter and Facebook posts.
The party - which is investigating a handful of candidates over links to groups such as the BNP and alleged racist and homophobic comments - said it did not condone "unpalatable views".
A spokesman insisted it would not bow to a "political lynch mob".
The row came as emails leaked to the Observer revealed that one of the party's MEPs is concerned about excessive "political correctness" among new recruits.
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