National Council for Civil Liberties' paedophile links
26 February 2014 Last updated at 00:33 GMT
Harriet Harman has said she "regrets" a civil liberties group she once worked for had links to pro-paedophile campaigners in the 1970s but insisted she had "nothing to apologise for".
The National Council for Civil Liberties granted "affiliate" status to the Paedophile Information Exchange.
The Daily Mail has urged the deputy Labour leader to explain this link.
But Ms Harman has accused the newspaper of "smear and innuendo" and said it "should be apologising".
Newsnight's Laura Kuenssberg has been trawling through NCCL files, to examine exactly what links it had with the PIE.