The NHS Commissioning Board is likely to place extensive restrictions on the powers of commissioning consortia in cases where it believes they are “not ready” to take on their new role, HSJ understands.

Department of Health officials are understood to have been concerned by politicians’ suggestions that consortium commissioning could be made permanently “optional” with primary care trusts or PCT clusters remaining in some areas.

Senior sources said the DH believed the plan would be unworkable due to technical difficulties, including dividing budgets between different forms of overlapping organisations and the parallel running cost of two separate systems.

There is also concern the public and others would be confused about who is responsible for commissioning.

Officials accept the need for the transition to be significantly slowed and that in many areas consortia are unlikely to be ready by 2013. But they are arguing this could instead be achieved by placing extensive conditions and restrictions on up to 80 per cent of consortia.

These restrictions could include consortia initially being given only part of the budget for their patch, with the rest controlled by the commissioning board. They could also be told their decisions must be approved by the national board, have external management and development support imposed on them, or be told to work with more developed nearby consortia.

David Cameron this week said the government would “make sure local commissioning only goes ahead when groups of GPs are good and ready”.

He suggested this could be achieved by giving the NHS Commissioning Board the role of “oversee[ing] commissioning on behalf of the secretary of state… providing the support to local commissioners, and carrying out commissioning themselves where necessary”.

The approach has been foreshadowed in recent months with NHS chief executive Sir David Nicholson saying conditions could be used in what was expected to be a small number of cases. But HSJ understands it could now be applied more widely.

NHS sources said in some regions only about one in five consortia looked likely to be ready to take on full responsibility from April 2013, while in others it could be about a third.

One source said officials were comfortable with the April 2013 deadline being moved, if that was proposed by politicians, but that a “patchwork” commissioning landscape of consortia and PCTs would be “almost impossible” to implement.

Conditions on consortia would be decided by the authorisation process. Officials say consortia would get “clear development plans” for when they take on further responsibility.