"Well over half" of the future NHS commissioning budgets have already been delegated to clinical commissioning groups (CCGs), "and the number is rising all the time," Health Secretary Andrew Lansley has told CCG clinical and managerial leads.

In a letter, Mr Lansley reminds the leads that, from April 1, 2013, they will become statutory NHS budget holders in their own right.

"This means you will have the freedom to prioritise resources in ways that best suit the needs of your population - without being second-guessed - and to reinvest all efficiency savings you make directly back into front-line patient care." he writes.

As well as the CCG clinical and managerial leads, Mr Lansley has also written to the chief executives of NHS trusts and NHS foundation trusts and to local authorities, to explain what the newly-passed Health and Social Care Act will mean for them and their staff.

"You will…have the freedom to pursue innovative ways of delivering care that delivers better results for your patients," he tells the CCG leads, adding: "you will also have the freedom to determine where you commission services."

"I want to reassure you that the breadth and scope of competition in the NHS is something that you will determine, in the interest of your patients. It will not be imposed upon you from Whitehall," he stresses.

To the NHS trust chief executives, he says that the Act will "give you genuine operational independence to determine how best to meet the needs of your commissioners." He reminds them that they are in the process of becoming NHS foundation trusts, which will ensure that they are a sustainable organisation and give them far greater operational freedom to organise services in the ways they know will deliver better care for their patients.

"This will mean you will be able to develop more innovative services, and you will be able to merge with, or acquire, other NHS foundation trusts and NHS trusts without the explicit approval of Monitor and without a burdensome legislative process. Because you are an NHS trust. you will suffer no disadvantage from an arbitrary cap on private income once you become an NHS foundation trust, so long as you demonstrate how it benefits your NHS services. In addition, there will not be any better deals on the table for private providers that you cannot access," he says.

His letter to the foundation trust chief executives reassures them that the Act prevents the government, or anyone else in the NHS, from discriminating against them in favour of the private sector. "I know from my discussions with some of you in the past just how frustrated you have felt about this practice. The Act prevents this in future, by law," he writes.

And the government's ambitions for health and social care "can only be realised with the enthusiastic contribution of local government," the Health Secretary writes to local authorities' chief executives and their directors of adult social services and of children's services.

The Act puts local government in its rightful place at the core of the health and care service and gives them, for the first time since the 1970s, statutory responsibility for commissioning public health services, he tells the authorities.

"I know how some of you have been frustrated by the fragmentation of public health responsibilities, which has existed for decades. The Act puts that right, by bringing that responsibility back together - allowing you to develop holistic, integrated public health services that are more effective at tackling long-term health challenges like obesity, smoking and alcohol misuse," he writes.

"I hope you will take maximum advantage of your new powers and freedoms," Mr Lansley tells all the groups.