Harriet Harman lashed out at the Daily Mail last night, in an attack which saw her accuse the paper of publishing photos of "very young girls".
The deputy Labour leader has been the subject of several front page Mail treatments in recent days accusing her of acting as legal officer for the National Council for Civil Liberties (NCCL) while it was affiliated with the Paedophile Information Exchange (PIE), a group which spoke positively about sex between adults and children.
"It is ironic that they're accusing me of supporting indecency in relation to children when they themselves are not above producing photographs of very young girls, titivating photographs in bikinis, so, you know, I stand by what I was doing at NCCL and I stand by what I was doing all the way through," she said on Newsnight.
"If there's anybody who has over the years supported indecency, it is much more the Daily Mail than it is me and that's the frank truth of it."
Harman said the tabloid was trying to smear her by association.
"They've made these allegations before and they're so outlandish," she said.
"They've put it on their front page three times and they're whipping up such an ugly insinuation that I felt it was really important to respond to them."
Harman stopped short of saying she regretted the rules allowing for PIE to affiliate with the NCCL, last night, but she did so through an aide this morning.
"[Harman] regrets the existence of PIE and she regrets their involvement with NCCL before she joined, although it was immaterial to her work," they said.
"She stands by the statement from yesterday and she is certainly not going to apologise to the Daily Mail."
Harman's husband, Labour MP Jack Dromney, has also been targeted by the newspaper and issued an angry statement in response.
"During my time on the NCCL executive, I was at the forefront of repeated public condemnations of PIE and their despicable views," he said.
"Then, when I was elected chairman, I took them on."
Former Labour MP and health secretary Patricia Hewitt has also been the subject of Mail coverage but is yet to release a statement.
Harman and Dromey tried to wait out the Mail coverage and hope it would eventually come to a natural end, but their statements yesterday show they felt they had to deal with the insinuation head-on.
Whether that tactic will pay off is questionable. The comments have radically expanded the number of outlets covering the allegations and also threaten to open up another war between Labour and the Mail.
The battle comes just months after Ed Miliband came out the victor of a protracted media row sparked by the Mail's description of his father as a man who "hated Britain".
Ralph Miliband was a former RAF pilot who later became a Marxist academic. His son was able to point out that his father had been fighting Germany during a historic period in which the Mail published its infamous "Hurrah for the Blackshirts" headline praising Oswald Mosley and the British Union of Fascists.
Many media commentators have long been wary of the Daily Mail's treatment of women and particularly young girls. There have been repeated accusations that very young women are sometimes shown in potentially titillating positions on the website.
Women's groups also criticise the manner in which the paper's infamous 'sidebar of shame' harms women's self-image with a constant stream of commentary on even the slightest physical flaw of young female celebrities.
Harman was legal officer at the NCCL between 1978 and 1982, during which PIE was an affiliate – although that took place before her arrival.
Harman says any group could affiliate to the organisation and that no expulsion policy existed.
At the time there were 8,000 members and 1,000 affiliates of the NCCL.
The Mail has claimed that during this period the NCCL proposed legalising incest, wanted to lower the age of consent to ten and recommended watering down the law on child abuse images.
Harman said she has supported a reduction in the age of consent for gay sex, but never a lowering to ten. She said the document on incest was published before she joined the organisation.
On the issue of child abuse imagery, she said the group was campaigning to stop the criminalisation of pictures used for sex education or those taken on the beach or the bath by parents.
A spokesperson for the Mail said: "For ten weeks now the Mail has repeatedly asked three leading Labour figures to answer questions about the involvement of the NCCL, a body in which they played leading roles, with a vile paedophile group.
"The belated statements today of Ms Harman and her husband - full of pedantry and obfuscation - failed to answer the Mail's central points."