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.
More top news
The youngsters were found unharmed in a Toyota after it failed to stop on the M25.
Labour is facing the embarrassing prospect of coming third, behind the Conservatives, in the Scottish parliamentary elections.
The Independent Police Complaints Commission is considering publishing an unredacted report of what happened at the Battle of Orgreave.