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
Florida police have charged a man who decided to eat his pancakes in the middle of the street with "placing an obstruction in the road".
The reason for the shooting is unclear, but local media have reported it may be a settling of scores between criminals.
Most parts of the country will experience near unbroken sunshine after a chilly start to the day.