The accusations come amid fears ministers have not done enough to prepare for Brexit, with the official deadline for the UK to leave the EU just 49 days away.
“Too much of the work procured to date appears to have been focused on ‘thinking and shaping’ rather than getting practical things done,” the accounts committee said.
“This only compounds our concerns over the speed of preparations for Brexit across Whitehall.”
The report comes the day after ministers were forced to publish Operation Yellowhammer documents – the government’s “worst case assumptions” about what could happen if the UK crashes out of the EU without a deal on October 31.
A no-deal Brexit could lead to outbreaks of disease and shortages of medicine, fresh food and fuel, with the poorest hit worst, according to the papers.
They also warned of “a rise in public disorder”, panic buying at supermarkets and huge traffic jams in Kent as the EU imposes tariffs and checks on UK goods.
The government was required to publish the documents after Boris Johnson lost a vote in the Commons last week.
However, while MPs also voted in favour of forcing ministers to make public communications to, from and between the PM’s top team of Downing Street advisors about the suspension of parliament, the government refused.
Michael Gove, who is in charge of no-deal Brexit preparations, described the request as an “unprecedented, inappropriate and disproportionate” use of parliament.
HuffPost UK has contacted the Cabinet Office for a response to the PAC report.