Iain Duncan Smith has said fake quotes attributed to benefit claimants created by his department had "nothing to do" with him and were the fault of his civil servants.
Last week the department for work and pensions was caught out fabricating testimonials from people praising the government's welfare system.
The work and pensions secretary told Sky News today that he had launched an internal investigation to find out what had happened.
“Somebody along the way put up what was essentially meant to be an example of the kind of advice [given to claimants] and it ended up going out as a quote, which was quite peculiar and quite wrong," he said. "That sort of thing doesn't really happen, it has happened this one time."
Labour MP Debbie Abrahams, a member of the work and pensions committee, said Duncan Smith should resign over the "shady and unscrupulous behaviour". A petition calling for the work and pensions secretary to quit has also attracted over 50,000 signatures.
But Duncan Smith dismissed his critics. "Debbie Abraham bangs on the whole time about that and there reality is every times she asks a question, nine times out of 10 she is wrong," he said.
He said the error had been made in the operations department of the DWP not his office. "This is nothing to do with us. I at no stage saw this," he said. "Of course they got that one wrong."
The fake testimonials were featured on the DWP's website. One titled "Sarah's story", tells of a jobseeker being "really pleased" that a cut to her payments encouraged her to re-draft her CV.
Another told Zac's story: