Iain Duncan Smith has been caught up in a new row over his department's dodgy use of official figures, the fourth in a year.
The controversy erupted after top Department for Work and Pensions official Neil Couling tried to defend the government's Work Programme during a grilling by members of Parliament's work and pensions committee using unpublished data, which angered MPs as they did not have a chance to properly scrutinize the figures.
Labour member Sheila Gilmore complained to Sir Andrew Dilnot, chair of the UK Statistics Authority, who confirmed that "published official statistics should be referred to in public statements" and that alternative information should be used only in "exceptional circumstances".
Sir Andrew added: "It is a matter of regret that DWP’s usual practice, which would have ensured compliance with the National Statistician’s guidance, was not followed."
Labour MP Sheila Gilmore said: "By quoting data that wasn’t publicly available at the time, DWP official Neil Couling made it impossible for my colleagues and I on the Work and Pensions Committee to hold him – and the Ministers to whom he reports – to account. This bad practice must not happen again."
"This is just the latest statistical foul play from Iain Duncan Smith’s department that I’ve helped to expose over the past year.”
A DWP spokesperson said: "A committee member asked a direct question about the support we provide to the long-term unemployed, and this was answered in good faith with the most up-to-date and useful information to assist the committee in their work.
"DWP has an exceptional record on making data widely available to the general public, and on this occasion we felt it was a priority to provide the relevant information needed at the time, rather than providing a limited and out-of-date response."
This comes after the UK Statistics Authority earlier this month described DWP Data on sickness and disability benefit employment and support allowance as "potentially misleading" and questioned whether it should be classed a "national statistic”.
The watchdog rebuked the DWP in December for failing to fully explain problems they were experiencing in producing the same data and for not highlighting them soon enough.
Last May, Sir Andrew Dilnot rebuked Tory chairman Grant Shapps after he mistakenly suggested 900,000 ESA applicants had dropped their claim rather than go through a ‘fit for work’ test – the real figure was a mere 19,700.
Duncan Smith distanced himself from Shapps under questioning about the statistical error in December, telling MPs that Conservative Campaign Headquarters (CCHQ) had "conflated" figures and that the DWP did not know they were coming out.
Previously, Duncan Smith dismissed an official rebuke from the statistics watchdog for making misleading claims about the effectiveness of his benefit reforms - as he "believes" he was right and the UKSA was wrong.