NHS commissioning needs to work on a larger scale to guarantee it has the power to stand up to large providers such as hospitals, he told a King's Fund event on Wednesday.
Lord Warner added that the DoH should legislate to force health and social care commissioners to work together to coordinate care around patient pathways.
He said legislation was necessary because there was 'little evidence that you can do it by exhortation and encouragement'. Although some commissioners were working across traditional boundaries, he said, for 'laggards' there was currently little incentive to change.
He added that a proportion of NHS budgets should be transferred to the social care sector because the NHS had enjoyed rapid rises in funding that had not been mirrored in social care.