Minister dismisses claims he attempted to pin the blame for "shocking" failures in his flagship welfare reform on his senior official.
The BBC's head of HR, Lucy Adams, has admitted making a mistake in her evidence to a committee of MPs investigating excessive payoffs.
A spat has broken out between ex-BBC chief Mark Thompson and the Trust over large payoffs to departing staff.
TaxPayers' Alliance political director Jonathan Isaby says the principle of simplifying the benefits system is right but the implementation is "deeply flawed".
He added: "A horrendous amount of taxpayers' money has already been wasted and those responsible for that must be held to account.
"Such a fundamental reform of the welfare system was always going to be a challenge, but the approach of many officials in the Department for Work and Pensions has been little short of shambolic."
Following criticism of the implementation of Universal Credit, a Department of Work and Pensions spokeswoman has said the scheme will "ultimately bring a £38bn economic benefit to society."
She added: "This report doesn't take into account our new leadership team, or our progress on delivery. We have already taken comprehensive action including strengthening governance, supplier management and financial controls...
"We don't recognise the write-off figure quoted by the committee and expect this to be substantially less. The head of Universal Credit, Howard Shiplee, has been clear that there is real potential to use much of the existing IT. We will announce our plans for the next phase of UC delivery shortly."
A scathing review of the Government's flagship Universal Credit scheme found that some of the IT assets that have been delivered for the programme cannot be used and so must be written off.
Initial estimates suggest the write-offs could amount to at least £140 million.
– Public Accounts Committee report
We saw evidence that purchase orders with a total value of £8.7 million were approved by a personal assistant to the Programme Director.
In another case, two purchase orders, one for £22.6 million and one for £1.1 million, were approved by a personal assistant to the Programme Director whose delegated financial authority at the time of approvals was only £10 million.
When the Department made individual payments to suppliers these could not be linked to particular pieces of work that had been delivered.
The Government's flagship benefit reform has been savaged by MPs for "shocking" failures and "alarmingly weak" management that have already wasted at least £140 million.
Secretaries were allowed to authorise purchase orders worth more than £20 million, and in some cases it is unclear what suppliers have been paid for, according to a damning report by the Public Accounts Committee.
A BT spokeswoman said the company was "disturbed" by an MPs' report that claimed the government's rural broadband scheme was mismanaged and left the internet provider with a near monopoly.
We are disturbed by today's report, which we believe is simply wrong and fails to take on board a point-by-point correction we sent to the committee several weeks ago.
We have been transparent from the start and willing to invest when others have not.
It is therefore mystifying that we are being criticised for accepting onerous terms in exchange for public subsidy - terms which drove others away.
The taxpayer is undoubtedly getting value for money.
– BT spokeswoman
BT faces a payback period of around 15 years on its rural broadband investments in spite of the subsidies available.
The DCMS (Department for Culture, Media and Sport) has imposed a rigorous auditing process that ensures every penny is accounted for.
The government's £1.2bn rural superfast broadband scheme has been mismanaged and has left sole provider BT in a "quasi monopolistic position", the chairwoman of the Commons spending watchdog has said.
Margaret Hodge, Public Accounts Committee Chair, said: "Overall, BT is supposed to provide at least 90% coverage in rural areas but it is preventing local authorities from publishing proper information on the areas the company will and will not cover.
"Details of speed and coverage in each local project are also being kept confidential, preventing other suppliers from developing schemes aimed at reaching the remaining 10% of premises and stopping communities and others from identifying alternative ways of providing superfast broadband."
Former BBC director general Mark Thompson has said tonight: "The first questions I want to answer are ones from the MPs and to put Parliament first".
Mr Thompson said he had "made a submission" to the Public Accounts Committee and did not want to make any public statements ahead of his appearance before MPs on Monday.
He has accused BBC Trust boss Lord Patten and trustee Anthony Fry of "fundamentally misleading" the committee in July when they gave evidence on senior staff payouts at the corporation.
It has emerged that the BBC has written to four former staff, whose pay-offs were investigated by the National Audit Office, to tell them they could be named to the committee.
In written evidence to MPs, head of corporate affairs Andrew Scadding, said the four had "resigned at the time of well publicised operational incidents at the BBC".
They are believed to include former BBC1 boss Peter Fincham who reportedly got a £500,000 pay-off when when he left the corporation in the wake of a scandal sparked by misleading footage of the Queen.
In written evidence published today, the BBC's head of HR, Lucy Adams admitted drafting a memo outlining plans for pay-offs to deputy director general Mark Byford and marketing boss Sharon Baylay.
She had initially told MPs she had not seen the note send by former Director General Mark Thompson to the then Chairman of the BBC Trust.