Ministers want to see polyclinics set up across England
Ministers have sought to allay fears over the forthcoming overhaul of the NHS in England.
Lord Darzi, who is in charge of the review which will see care moved to new GP-led health centres, said any changes would benefit patients.
He also said councils would be able to challenge the plans, which are due to be set out by nine regional teams following consultation exercises.
But it comes as doctors accused the government of undermining GP practice.
Lord Darzi's interim report in October called for the GP-led centres - super surgeries where GPs work alongside social care staff, hospital teams and nurses - to be set up across the country.
However, he has always said plans have to be drawn up locally and that is what will now be published in the coming weeks - with the East of England expected to set out its plans first on Monday.
Lord Darzi, who was asked to carry out the review shortly after Gordon Brown became prime minister, is then due to pull them all together in a final report in the summer to mark the 60th anniversary of the NHS.
But ahead of the nine regional plans, which do not include London where proposals for a network of clinics have already been put forward, Lord Darzi made a number of pledges.
He said change would only be carried out on the basis of clear evidence of benefit to patients and be led by doctors.
He also promised existing services would not be withdrawn until new and better services were available, while local areas will be able to challenge reforms through councils' power to hold health services to account.
Lord Darzi, who is a practising surgeon, said: "The nature of health care means services will always need to change and sometimes that means reorganising how services are provided.
"This is not about change for change's sake. It's about change for the right reasons, improving quality of care for patients and saving lives."
But the British Medical Association said the changes risked destroying GP care.
Dr Laurence Buckman, chairman of the BMA's GPs committee, said: "Although large health centres may work in some areas, the government wishes to impose the polyclinic model on every trust in the country regardless of need or demand.
"Private commercial companies would also be able to bid for the new centres, leading to fears that they will be more interested in their shareholders than patients.
"The government appears to be moving further away from the personalised care it claims to aspire to."
And Karen Jennings, of Unison, agreed. "My fear is that, even with the pledges, change will herald the increased use of private companies in the NHS."
But the Patients Association welcomed Lord Darzi's promises and called for local decision-makers to respect them.