Iain Duncan Smith is under mounting pressure over the chaos in introducing his £2.4bn shake-up of the benefits system after being accused of not telling Parliament about the problems.

Labour seized on a damning report by the Government’s auditors as evidence of a “cover-up” over the delays in phasing in the flagship universal credit scheme. The Opposition demanded an apology and suggested the Work and Pensions Secretary should “consider his conscience” because misleading Parliament is traditionally a resignation issue.

Mr Duncan Smith insisted that he did not mislead MPs. He believed when he made his progress report in March that universal credit would be delivered “on time, in budget” in 2017, and his view had not changed.

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He was summoned to the Commons today to answer an urgent question on the highly critical National Audit Office report, which said the integration of several means-tested benefits was beset by “weak management, ineffective control and poor governance” and that £34m had been wasted.

Mr Duncan Smith blamed his civil servants for not giving him a full picture of the teething troubles. “At the end of the day, you are only as good as the information given to you,” he said. He admitted he had “lost faith” in his department’s civil servants, which was why he changed the programme. He insisted he took full responsibility for the programme but did not apologise for the problems so far.

Liam Byrne, the shadow Work and Pensions Secretary, demanded to know why the minister did not tell MPs in March that the reform timetable was being changed even though it was “inconceivable” he did not know. He told the minister: “You have let this House form a view of universal credit which the nation’s auditor says is wrong.”

Mr Byrne said: “Universal credit is a Titanic-sized disaster which [Mr Duncan Smith] has tried to hide with cover-up after cover-up.” He added: “The most charitable explanation for this is he’s lost control of the programme and he’s lost control of the department and he must now correct the record, he must now apologise to the House and he must now convene cross-party talks to get this project back on track. The quiet man must not become the cover-up man.”

Barry Gardiner, a Labour MP, asked the minister: “Why did you not give a more candid account to Parliament in March?”

Mr Duncan Smith dismissed Mr Byrne’s attack as “suitably pathetic.” He said the full timetable would be set out this autumn, and insisted repeatedly the project would be delivered “on time and in budget”. Everyone now on jobseeker’s allowance and tax credits would be receiving universal credit by the 2015 election, he added.

He told Mr Byrne: “When I got concerned about the delivery schedule I made changes and I intervened. I have brought the right people in to do this and I stand by that. I will not take lessons from you and your party. The reality is ... that we check these programmes while they are progressing and if there are changes that need to be made, we make them…. something [Labour] never did in the whole of their time in government.”

Downing Street insisted the Prime Minister had full confidence that universal credit would be introduced on schedule. But a Labour source said last night: “David Cameron must now be wondering if Iain Duncan Smith is up to the job. It’s an open secret across Whitehall that his department is in chaos and costing the taxpayer millions of pounds.”

Rob O'Neill, assistant general secretary of the FDA union representing senior officials, said Mr Duncan Smith’s remarks “ represent a growing blame culture in government where ministers blame civil servants but fail to take any responsibility when things go wrong or overrun. Ministers can do this because they know that civil servants are unable to publicly answer back.”