Leadership at Bedford Hospital has been described as "weak" in an independent report into last year's paediatric department problems.
Some services for under-19s were suspended last summer with the trust saying staff shortages were to blame.
The move came after junior doctors were withdrawn over safety worries. The report said the board had effectively ignored the concerns of trainees.
The hospital said it regretted its "failure to act robustly".
Bedford Hospital NHS Trust suspended children's A & E services, planned surgery and overnight observation from 1 August.
It acted when seven medical trainees were removed by Health Education East of England (HEEoE) and the General Medical Council (GMC) after junior doctors expressed concern about inadequate levels of supervision.
Patients were transferred to Milton Keynes Hospital or another neighbouring hospital.
The hospital-commissioned report, by health policy consultant Sally Williams, said the hospital had "failed to demonstrate compliance with fundamental standards for postgraduate training".
It said the board was warned on three occasions in 2012 that the trainees could be withdrawn, but failed to act properly.
Poor communication between trainees and clinicians has also been highlighted, as has the "absence of a strategic vision" and a complacency which pointed to "a high tolerance of unsafe practice".
"There is evidence that clinical leadership within the department has been weak, lacking in vision and assertiveness," the report summary said.
The trust's response to concerns about paediatric training can "at best be described as muted, and at worst 'non-existent'", it added.
The report also made ten recommendations to the trust board meeting in January to ensure junior medical staff support continued to improve.
These include the introduction of a standing item on training at trust board meetings to include trainee feedback.
A hospital spokesman said the report was a "sober reminder of the mistakes and missed opportunities" and apologised for months of "disruption and undoubted distress".
Chief executive, Stephen Conroy said "fundamental changes" had been made in the past six months, including the recruitment of additional medical and nursing staff, and the "vast majority" of children's services, were now being provided at its Riverbank Children's Unit.
"We know we still have work to do to continue to embed the changes we have made, sustain improvement and transform our culture from board to bedside," he said.
"I feel deep personal regret that patients and local families suffered the consequences of our failure to act robustly enough to tackle issues around support for junior doctors in paediatrics before it reached crisis point."
An internal assessment will determine when the hospital is ready to apply to return junior doctors to paediatric training posts.