The chairperson of the Public Accounts Committee (PAC) said she had not been approached by the Work and Pensions Secretary over singling out the departments' chief civil servant in the report revealing the Universal Credit scheme "wasted £140 million."
The Times reported that Mr Duncan Smith and members of his parliamentary team approached Tory members of the PAC to ensure that the department's chief civil servant Robert Devereux was singled out for criticism.
Sidestepping the question over wider Tory lobbying, she told the BBC:
Iain Duncan Smith didn't approach me. Beyond that I can't comment.
She went on to criticise the "fortress culture" at the Department of Work and Pensions, which meant "only good news was reported and problems were denied".
More top news
Democrat presidential hopeful Hillary Clinton begins her New Hampshire campaign but young and female voters are opting for Bernie Sanders.
Some southern counties have seen their windiest winds of the winter so far today.
A man in his 50s has been shot dead in Dublin, three days after a fatal shooting at a nearby hotel.