The head of Whitehall's spending watchdog has taken the highly unusual step of publicly rebuking Work and Pensions Secretary Esther McVey about her response to its critical report on the roll-out of Universal Credit.
In an open letter to Ms McVey, Auditor General Sir Amyas Morse said that elements of her statement to Parliament on the report were incorrect and unproven.
He said it was "odd" that she had told MPs that the National Audit Office report did not take into account the impact of recent changes to the administration of the welfare benefit, when it had in fact been "fully agreed" by senior officials at the Department for Work and Pensions only days before.
In its report on June 15, the National Audit Office (NAO) highlighted the hardship caused to claimants by delays in receiving payments under UC.
It concluded that the new system - being gradually introduced to replace a number of benefits - was "not value for money now, and that its future value for money is unproven".