Health Secretary Andrew Lansley's controversial NHS reforms are reportedly set to be heavily criticised by an influential cross-party group of MPs.
The Observer said the Commons Health Committee would this week say the proposals were obstructing efforts to make the NHS more efficient and failed to address the needs of an ageing population.
The paper said the committee, chaired by Conservative former health secretary Stephen Dorrell had concluded the plan to restructure the NHS in England and devolve more power to GPs was making it more difficult to achieve the target of £20 billion in efficiency savings by 2014-15.
It quoted a "late draft" of the committee's report as saying: "The reorganisation process continues to complicate the push for efficiency gains.
"Although it may have facilitated savings in some cases we heard that it more often creates disruption and distraction that hinders the ability of organisations to consider truly effective ways of reforming service delivery and releasing savings."
Shadow health secretary Andy Burnham said it was now clear Mr Lansley's reform plan had been a "monumental mistake" and called for a Government rethink.
"This report is a damning indictment of the Government's mishandling of the NHS," he said. "It is time for David Cameron to listen to what doctors, nurses and now his own senior MPs are saying and call a halt to this reckless reorganisation."
Health minister Simon Burns, however, insisted the Government was determined to put the NHS on a sustainable footing.
"We all know the NHS is facing pressures from an ageing population and the increasing costs of medicines. That's why we are spending an extra £12.5 billion on the NHS. We have also made £7 billion in efficiency savings as performance has improved," he said.
"These will all help in the short term, but if we are to put the NHS on a sustainable footing for the future reform is essential. Our modernisation plan will put doctors in charge, slash bureaucracy and give much more power to patients."